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    <div style="text-align: center; font-family: 'Times New Roman', Times, serif; font-size: 10pt; font-weight: bold;">As filed with the Securities and Exchange Commission on June 12, 2019</div>
    <div style="text-align: right;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Registration No. 33</font><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">3</font><font style="font-size: 10pt;
        font-family: 'Times New Roman', Times, serif;">-</font></div>
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    <div style="text-align: center; margin-top: 4pt;"><font style="font-size: 18pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">UNITED STATES</font></div>
    <div style="text-align: center;"><font style="font-size: 18pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">SECURITIES AND EXCHANGE COMMISSION</font></div>
    <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">Washington, D.C. 20549</font></div>
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    <div style="text-align: center; margin-top: 12pt;"><font style="font-size: 18pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">FORM S-8</font></div>
    <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold; font-style: italic;">REGISTRATION STATEMENT</font></div>
    <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold; font-style: italic;">UNDER</font></div>
    <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold; font-style: italic;">THE SECURITIES ACT OF 1933</font></div>
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    <div style="text-align: center; margin-top: 12pt;"><font style="font-size: 18pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">CABOT MICROELECTRONICS CORPORATION</font></div>
    <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">(Exact name of registrant as specified in its charter)</font></div>
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            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">Delaware</font></div>
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            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">36-4324765</font></div>
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            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">(State of Incorporation)</font></div>
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            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
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            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">(IRS Employer</font></div>
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">Identification No.)</font></div>
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    <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">870 North Commons Drive</font></div>
    <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">Aurora, Illinois 60504</font></div>
    <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">(630) 375-6631</font></div>
    <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">(Address, including Zip Code, and Telephone Number, Including Area Code, of Registrant&#8217;s Principal Executive Offices)</font></div>
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    <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">Cabot Microelectronics Corporation 2012 Omnibus Incentive Plan (as amended)</font></div>
    <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">(Full Title of the Plan)</font></div>
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    <div style="text-align: center; margin-top: 12pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">H. Carol Bernstein</font></div>
    <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">Vice President, Secretary and General Counsel</font></div>
    <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">870 North Commons Drive</font></div>
    <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">Aurora, Illinois 60504</font></div>
    <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">(630) 375-5461</font></div>
    <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">(Name, Address, including Zip Code, and Telephone Number, including Area Code, of Agent for Service)</font></div>
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    <div style="text-align: left; margin-top: 12pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a
        smaller reporting company, or an emerging growth company. See the definitions of &#8220;large accelerated filer,&#8221; &#8220;accelerated filer,&#8221; &#8220;smaller reporting company,&#8221; and &#8220;emerging growth company&#8221; in Rule 12b-2 of the Exchange Act.</font></div>
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            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Large&#160;accelerated&#160;filer</font></div>
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            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
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            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Accelerated&#160;filer</font></div>
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            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
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            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Non-accelerated&#160;filer</font></div>
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            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
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            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#9744;</font>&#160;&#160;(Do not check if a smaller reporting company)</font></div>
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            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;&#160;</font></div>
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          <td style="width: 26.18%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Smaller&#160;reporting&#160;company</font></div>
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            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
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            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#9744;</font></div>
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          <td style="width: 1.2%; vertical-align: bottom;">&#160;</td>
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            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Emerging growth&#160;company</font></div>
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          <td style="width: 0.6%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
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            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#9744;</font></div>
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      <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;"><font style="background-color: #FFFFFF; font-size: 10pt; font-family: 'Times New Roman', Times, serif;">If an emerging growth company,
            indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section&#160;7(a)(2)(B) of the Securities Act. </font><font style="background-color: #FFFFFF; font-size: 10pt; font-family: 'Segoe UI Symbol', sans-serif;">&#9744;</font></font></div>
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      <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">CALCULATION OF REGISTRATION FEE</font></div>
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          <td style="width: 35.21%; vertical-align: bottom;" rowspan="3" colspan="4">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Title of Securities to</font></div>
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">be Registered)</font></div>
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          <td style="width: 11.68%; vertical-align: bottom;" rowspan="3">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Amount to be</font></div>
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Registered (1)(2)</font></div>
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            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Proposed Maximum</font></div>
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Offering Price per Share (3)</font></div>
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            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Proposed Maximum</font></div>
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Aggregate Offering</font></div>
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Price (4)</font></div>
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          <td style="width: 13.61%; vertical-align: bottom;" rowspan="3">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Amount of</font></div>
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Registration Fee (2)</font></div>
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          <td style="width: 0.9%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
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          <td style="width: 35.21%; vertical-align: bottom;" colspan="4">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Common Stock par value $.001 per share</font></div>
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          </td>
          <td style="width: 11.68%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">43,443.00</font></div>
          </td>
          <td style="width: 0.85%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 0.54%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 19.1%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">$104.99</font></div>
          </td>
          <td style="width: 0.85%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 0.54%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 13.86%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">$4,561,080.57</font></div>
          </td>
          <td style="width: 0.85%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 0.54%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 13.61%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">$552.80</font></div>
          </td>
          <td style="width: 0.5%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 100%; vertical-align: bottom;" colspan="18">
            <div style="text-align: left;"><font style="font-family: Times, serif; font-size: 1pt;">&#160;</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 2.88%; vertical-align: top;" colspan="2">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 2.32%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">(1)</font></div>
          </td>
          <td style="width: 0.9%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 93.9%; vertical-align: top;" colspan="14">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the &#8220;Securities Act&#8221;), this Registration Statement shall also
                cover any additional shares of <font style="background-color: #FFFFFF; font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Cabot Microelectronics Corporation (&#8220;Cabot Microelectronics&#8221;) common stock, </font><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">par value $0.001 per share (&#8220;CMC Common Stock&#8221;),</font><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font>which become issuable under
                the Cabot Microelectronics Corporation 2012 Omnibus Incentive Plan, as amended (the &#8220;Plan&#8221;) by reason of any stock dividend, stock split, recapitalization or any other similar transaction effected without the receipt of consideration which
                results in an increase in the number of CMC Common Stock.</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 2.88%; vertical-align: top;" colspan="2">&#160;</td>
          <td style="width: 2.32%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">(2)</font></div>
          </td>
          <td style="width: 0.9%; vertical-align: top;">&#160;</td>
          <td style="width: 93.9%; vertical-align: top;" colspan="14">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Represents the <font style="background-color: #FFFFFF; font-size: 10pt; font-family: 'Times New Roman', Times, serif;">number of shares
                  of CMC Common Stock</font> reserved for issuance <font style="background-color: #FFFFFF; font-size: 10pt; font-family: 'Times New Roman', Times, serif;">as a result of the conversion of </font><font style="font-size: 10pt; font-family:
                  'Times New Roman', Times, serif;">restricted stock unit awards relating to shares of common stock of KMG Chemicals, Inc. (&#8220;KMG&#8221;), par value $0.01 per share (&#8220;KMG Common Stock&#8221;), (each, a &#8220;KMG Equity Award&#8221;)</font><font style="font-size:
                  10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">granted on or following August&#160;14, 2018</font><font style="background-color: #FFFFFF; font-size:
                  10pt; font-family: 'Times New Roman', Times, serif;"> and outstanding as of </font>immediately prior to the effective time of the merger into restricted stock unit awards relating to shares of CMC Common Stock.</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 2.88%; vertical-align: top;" colspan="2">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 2.32%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">(3)</font></div>
          </td>
          <td style="width: 0.9%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 93.9%; vertical-align: top;" colspan="14">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Estimated solely for the purpose of determining the registration fee pursuant to Rules 457(c) and 457(h) of the Securities Act and based
                on the average of the high and low prices of a share of CMC Common Stock as reported on the NASDAQ Global Select Market on June 7, 2019.</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 2.88%; vertical-align: top;" colspan="2">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 2.32%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">(4)</font></div>
          </td>
          <td style="width: 0.9%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 93.9%; vertical-align: top;" colspan="14">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">This Registration Statement registers additional shares of CMC Common Stock issuable pursuant to the same employee benefit plan for
                which Registration Statement No.&#160;333-179955 is currently effective. Accordingly, pursuant to Instruction E on Form S-8, the registration fee is being paid with respect to the additional securities only.</font></div>
          </td>
        </tr>

    </table>
    <div style="margin-top: 6pt; margin-bottom: 6pt;"><br>
    </div>
    <div id="DSPFPageBreakArea" style="clear: both; margin-top: 10pt; margin-bottom: 10pt;">
      <div id="DSPFPageBreak" style="page-break-after:always;">
        <hr noshade="noshade" style="margin: 4px 0px; width: 100%; border-width: 0; height: 2px; color: #000000; background-color: #000000; clear: both;"></div>
    </div>
    <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">EXPLANATORY NOTE</font></div>
    <div><br>
    </div>
    <div style="text-align: left; text-indent: 36pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Pursuant to the Agreement and Plan of Merger,
          dated as of August 14, 2018 (the &#8220;merger agreement&#8221;), by and among Cabot Microelectronics, KMG and Cobalt Merger Sub Corporation, a Texas corporation and a wholly owned subsidiary of Cabot Microelectronics (&#8220;Merger Sub&#8221;), Merger Sub merged with
          and into KMG, with KMG becoming a direct, wholly owned subsidiary of Cabot Microelectronics (the &#8220;merger&#8221;). In connection with the merger, and as of the effective time of the merger (the &#8220;Effective Time&#8221;), each KMG Equity Award</font><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">granted on or following August&#160;14, 2018 was converted into a corresponding award relating
          to shares of CMC Common Stock subject to the terms of the applicable award agreement. Section 6.6 of the Plan permits Cabot Microelectronics to grant awards to person who became employees, directors or advisors in connection with the merger for
          equity incentives held by them in KMG. </font><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">This registration statement has been filed for the purpose of registering CMC Common Stock issuable upon the exercise of
          such awards.</font></font></div>
    <div><br>
    </div>
    <div style="background-color: #FFFFFF;">
      <div style="text-align: left; text-indent: 36pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Pursuant to General Instruction E of Form S-8, the contents of Registration Statement No. 333-<font style="font-size: 10pt;
            font-family: 'Times New Roman', Times, serif;">179955</font> are incorporated herein by reference, to the extent not amended hereby.</font></div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div><br>
      </div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">PART I</font></div>
      <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS</font></div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div><br>
      </div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div style="text-align: left; text-indent: 36pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">We shall send or give to each participant in the Plan the document(s) containing the information specified in Part I of
          Form S-8 as specified by Rule 428(b)(1) of the Securities Act. In accordance with the rules and regulations of the Securities and Exchange Commission (the &#8220;Commission&#8221;), such documents are not being filed with or included in this Registration
          Statement. These documents, and the documents incorporated by reference into this Registration Statement pursuant to Item 3 of Part II of this Registration Statement, taken together, constitute a prospectus that meets the requirements of Section
          10(a) of the Securities Act.</font></div>
      <div><br>
      </div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">PART II</font></div>
      <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">INFORMATION REQUIRED IN THE REGISTRATION STATEMENT</font></div>
      <div><br>
      </div>
    </div>
    <table cellspacing="0" cellpadding="0" id="z99816a07368d483c95486daead8badda" style="font-family: 'Times New Roman', Times, serif; font-size: 10pt; width: 100%;">

        <tr>
          <td style="width: 6.84%; vertical-align: middle;">&#160;</td>
          <td style="width: 1.16%; vertical-align: middle;">&#160;</td>
          <td style="width: 92%; vertical-align: middle;">&#160;</td>
        </tr>

    </table>
    <div style="background-color: #FFFFFF;">
      <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">Item 3. Incorporation of Documents by Reference.</font></div>
      <div><br>
      </div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div style="text-align: left; text-indent: 36pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">We have filed with the Commission and hereby incorporate by reference the following documents:</font></div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div><br>
      </div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div>
        <table cellspacing="0" cellpadding="0" id="zc7e5606685624f07a02457db241988d8" class="DSPFListTable" style="font-family: 'Times New Roman', Times, serif; font-size: 10pt; width: 100%;">

            <tr>
              <td style="width: 18pt; vertical-align: top; align: right;">
                <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">(a)</font></div>
              </td>
              <td style="width: auto; vertical-align: top;">
                <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Our Annual Report on Form 10-K for the fiscal year ended September 30, 2018 filed with the Commission on November 13, 2018;</font></div>
              </td>
            </tr>

        </table>
      </div>
      <div>
        <table cellspacing="0" cellpadding="0" id="zbdc9268799d949a6bf212355fc917745" class="DSPFListTable" style="font-family: 'Times New Roman', Times, serif; font-size: 10pt; width: 100%;">

            <tr>
              <td style="width: 18pt; vertical-align: top; align: right;">
                <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">(b)</font></div>
              </td>
              <td style="width: auto; vertical-align: top;">
                <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Our Quarterly Reports on Form 10-Q for the quarter ended December 31, 2018 filed with the Commission on February 11, 2019 and for
                    the quarter ended March 31, 2019 filed with the Commission on May 10, 2019;</font></div>
              </td>
            </tr>

        </table>
      </div>
      <div>
        <table cellspacing="0" cellpadding="0" id="zdf7bcdb018c54a8f8ce3e8050757bebe" class="DSPFListTable" style="font-family: 'Times New Roman', Times, serif; font-size: 10pt; width: 100%;">

            <tr>
              <td style="width: 18pt; vertical-align: top; align: right;">
                <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">(c)</font></div>
              </td>
              <td style="width: auto; vertical-align: top;">
                <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Current Reports on Form&#160;8-K filed on November 15, 2018 (as amended by the Form 8-K/A filed on January 31, 2019), December 7, 2018,
                    January 24, 2019, March 6, 2019 and March 7, 2019 (excluding any information furnished under Items 2.02, 7.01 and 9.01 thereof); and</font></div>
              </td>
            </tr>

        </table>
      </div>
      <div>
        <table cellspacing="0" cellpadding="0" id="z4759d05616cb4871b38dac534b7e23fb" class="DSPFListTable" style="font-family: 'Times New Roman', Times, serif; font-size: 10pt; width: 100%;">

            <tr>
              <td style="width: 18pt; vertical-align: top; align: right;">
                <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">(d)</font></div>
              </td>
              <td style="width: auto; vertical-align: top;">
                <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">The description of CMC Common Stock contained in our Registration Statement on Form 8-A filed with the Commission on April&#160;3, 2000.</font></div>
              </td>
            </tr>

        </table>
      </div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div><br>
      </div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div style="text-align: left; text-indent: 36pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">In addition, all documents subsequently filed pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Securities Exchange
          Act of 1934, as amended, (the &#8220;Exchange Act&#8221;), prior to the filing of a post-effective amendment which indicates that all shares of CMC Common Stock subject to the Plan have been sold or which deregisters all of such shares then remaining unsold,
          shall be deemed to be incorporated by reference into this Registration Statement and to be a part hereof from the date of filing of such documents. Notwithstanding the foregoing, unless specifically stated to the contrary, none of the information
          disclosed by us under Items 2.02 or 7.01 of any current report on Form 8-K that we may from time to time furnish to the Commission will be incorporated by reference into, or otherwise included in, this Registration Statement. Any statement
          contained herein or in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded for purposes of this Registration Statement to the extent that a statement contained herein or in any
          subsequently filed document which also is or is deemed to be incorporated by reference herein modifies or supersedes such statement. Any such statement so modified or superseded shall not be deemed, except as so modified or superseded, to
          constitute a part of this Registration Statement.</font></div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;"><br>
          <font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;"><br>
          </font>Item 4. Description of Securities.</font></div>
      <div><br>
      </div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div style="text-align: left; text-indent: 36pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Not Applicable.</font></div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div><br>
      </div>
      <div style="clear: both; margin-top: 10pt; margin-bottom: 10pt;" id="DSPFPageBreakArea">
        <div style="page-break-after: always;" id="DSPFPageBreak">
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      </div>
      <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">Item 5. Interests of Named Experts and Counsel.</font></div>
      <div><br>
      </div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div style="text-align: left; text-indent: 36pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Not Applicable.</font></div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div><br>
      </div>
      <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">Item 6. Indemnification of Directors and Officers.</font></div>
      <div><br>
      </div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div style="text-align: left; text-indent: 36pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Section 145 of the Delaware General Corporation Law (the &#8220;DGCL&#8221;) provides that a corporation may indemnify directors and
          officers as well as other employees and individuals against expenses (including attorneys&#8217; fees), judgments, fines and amounts paid in settlement in connection with specified actions, suits and proceedings, whether civil, criminal,
          administrative, or investigative (other than an action by or in the right of the corporation &#8211; a &#8220;derivative action&#8221;), if they acted in good faith and in a manner they reasonably believed to be in or not opposed to the best interests of the
          corporation and, with respect to any criminal action or proceeding, had no reasonable cause to believe their conduct was unlawful. A similar standard is applicable in the case of derivative actions, except that indemnification only extends to
          expenses (including attorneys&#8217; fees) incurred in connection with the defense or settlement of such action, and the statute requires court approval before there can be any indemnification where the person seeking indemnification has been found
          liable to the corporation. The statute provides that it is not exclusive of other indemnification that may be granted by a corporation&#8217;s certificate of incorporation, bylaws, disinterested director vote, stockholder vote, agreement, or otherwise.</font></div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div><br>
      </div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div style="text-align: left; text-indent: 36pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Our bylaws and our certificate of incorporation require us to indemnify to the fullest extent authorized by the DGCL any
          person made or threatened to be made a party to an action, suit or proceeding, whether criminal, civil, administrative or investigative, by reason of the fact that he or she is or was a director or officer of Cabot Microelectronics, or is or was
          serving at the request of Cabot Microelectronics as a director, officer, employee or agent of another corporation or of a partnership, joint venture,&#160;trust or other enterprise.</font></div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div><br>
      </div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div style="text-align: left; text-indent: 36pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">As permitted by section 102(b)(7) of the DGCL, our certificate of incorporation eliminates the liability of a director to
          the corporation or its stockholders for monetary damages for such breach of fiduciary duty as a director, except for&#160;liabilities arising (a) from any breach of the director&#8217;s duty of loyalty to the corporation or its stockholders; (b) from acts
          or omissions not in good faith or which involve intentional misconduct or a knowing violation of law; (c) under section 174 of the DGCL; or (d) from any transaction from which the director derived an improper personal benefit.</font></div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div><br>
      </div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div style="text-align: left; text-indent: 36pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">We maintain primary and excess insurance policies insuring our directors and officers and those of our subsidiaries against
          certain liabilities they may incur in their capacity as directors and officers. Under these policies, the insurer, on our behalf, may also pay amounts for which we have granted indemnification to the directors or officers.</font></div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
      <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">Item 7. Exemption from Registration Claimed.</font></div>
      <div><br>
      </div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div style="text-align: left; text-indent: 36pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Not Applicable.</font></div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div><br>
      </div>
      <div style="clear: both; margin-top: 10pt; margin-bottom: 10pt;" id="DSPFPageBreakArea">
        <div style="page-break-after: always;" id="DSPFPageBreak">
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      </div>
      <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">Item 8. Exhibits.</font></div>
      <div><br>
      </div>
    </div>
    <table cellspacing="0" cellpadding="0" id="zc91bda983e6241c5b673ae16efaa7ccb" style="font-family: 'Times New Roman', Times, serif; font-size: 10pt; width: 100%;">

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          <td style="width: 10.24%; vertical-align: bottom; border-bottom: #000000 2px solid;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">EXHIBIT </font></div>
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">NO.</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: bottom; border-bottom: #000000 2px solid;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">DESCRIPTION</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">3.1</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">(Third) Amended and Restated By-Laws of Cabot Microelectronics Corporation (incorporated by reference to Exhibit 3.2 to the Registrant&#8217;s
                Current Report on Form&#160;8-K filed with the Commission on March 7, 2017).</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">3.2</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Form of Amended and Restated Certificate of Incorporation of Cabot Microelectronics Corporation (incorporated by reference to
                Exhibit&#160;3.3 to the Registrant&#8217;s Registration Statement on Form&#160;S-1 (No.&#160;333-95093) filed with the Commission on March&#160;27, 2000).</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">4.1</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Form of Cabot Microelectronics Corporation Common Stock Certificate (incorporated by reference to Exhibit&#160;4.1 to the Registrant&#8217;s
                Registration Statement on Form&#160;S-1 (No.&#160;333-95093) filed with the Commission on April&#160;3, 2000).</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">4.2</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Cabot Microelectronics Corporation 2012 Omnibus Incentive
                  Plan, as amended effective March 7, 2017 (incorporated by </font>reference to Exhibit&#160;10.61 to the Registrant&#8217;s Quarterly Report on Form&#160;10-Q filed with the Commission on May 5, 2017).</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">5.1</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Opinion of Wachtell, Lipton, Rosen &amp; Katz.</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">23.1</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Consent of Wachtell, Lipton, Rosen &amp; Katz (included in Exhibit&#160;5.1).</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">23.2</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Consent of PricewaterhouseCoopers LLP (Independent Registered Public Accounting Firm).</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div>&#160;</div>
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">23.3</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div>&#160;</div>
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Consent of KPMG, LLP (Independent Registered Public Accounting Firm).</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div>&#160;</div>
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">24.1</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div>&#160;</div>
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Power of Attorney (included in the signature page to this Registration Statement).</font></div>
          </td>
        </tr>

    </table>
    <div style="background-color: #FFFFFF;">
      <div><br>
      </div>
      <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">Item 9. Undertakings.</font></div>
      <div><br>
      </div>
    </div>
    <div style="text-align: left; margin-top: 6pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">(a) The Registrant hereby undertakes:</font></div>
    <div style="text-align: left; margin-top: 12pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">(1) To file, during any period in which offers or sales are being made, a post-effective amendment to this registration
        statement:</font></div>
    <div style="text-align: left; margin-top: 12pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">(i) To include any prospectus required by Section&#160;10(a)(3) of the Securities Act.</font></div>
    <div style="text-align: left; margin-top: 12pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">(ii) To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the
        most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of
        securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with
        the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20% change in the maximum aggregate offering price set forth in the &#8220;Calculation of Registration Fee&#8221; table in the effective
        registration statement.</font></div>
    <div style="text-align: left; margin-top: 12pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">(iii) To include any material information with respect to the plan of distribution not previously disclosed in the
        registration statement or any material change to such information in the registration statement;</font></div>
    <div style="text-align: left; margin-top: 12pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-style: italic;">Provided, however</font>,
        that paragraphs (a)(1)(i) and (a)(1)(ii) herein do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the Commission by the Registrant pursuant
        to Section&#160;13 or Section&#160;15(d) of the Exchange Act (15 U.S.C. 78m or 78o(d)) that are incorporated by reference in the registration statement.</font></div>
    <div style="text-align: left; margin-top: 12pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">(2) That, for the purpose of determining any liability under the Securities Act, each such post-effective amendment shall be
        deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.</font></div>
    <div style="text-align: left; margin-top: 12pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">(3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain
        unsold at the termination of the offering.</font></div>
    <div style="text-align: left; margin-top: 12pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">(b) The Registrant hereby undertakes that, for purposes of determining any liability under the Securities Act, each filing of
        the Registrant&#8217;s annual report pursuant to Section&#160;13(a) or Section&#160;15(d) of the Exchange Act (and, where applicable, each filing of an employee benefit plan&#8217;s annual report pursuant to Section&#160;15(d) of the Exchange Act) that is incorporated by
        reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.</font></div>
    <div style="text-align: left; margin-top: 12pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">(c) Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers and
        controlling persons of the Registrant pursuant to the foregoing provisions, or otherwise, the Registrant has been advised that in the opinion of the Commission such indemnification is against public policy as expressed in the Securities Act and is,
        therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the Registrant of expenses incurred or paid by a director, officer or controlling person of the Registrant in the successful
        defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the Registrant will, unless in the opinion of its counsel the matter has been settled by
        controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act and will be governed by the final adjudication of such issue.</font></div>
    <div id="DSPFPageBreakArea" style="clear: both; margin-top: 10pt; margin-bottom: 10pt;">
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    </div>
    <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">SIGNATURES</font></div>
    <div style="text-align: left; margin-top: 12pt;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable
        grounds to believe that it meets all of the requirements for filing on Form&#160;S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Aurora, State of Illinois, on
        June 12, 2019.</font></div>
    <table cellspacing="0" cellpadding="0" border="0" id="zfc44027aec2e48a2b55b9c317f5088c5" style="font-family: 'Times New Roman', Times, serif; font-size: 10pt; width: 100%;">

        <tr>
          <td style="width: 29%; vertical-align: middle; text-align: center; padding-bottom: 2px;"><br>
          </td>
          <td style="width: 6%; vertical-align: middle; text-align: center; padding-bottom: 2px;">&#160;</td>
          <td style="width: 36%; vertical-align: middle; text-align: center; border-bottom: 2px solid rgb(0, 0, 0);"><font style="font-size: 10pt; font-family: &quot;Times New Roman&quot;,Times,serif;">CABOT MICROELECTRONICS CORPORATION</font> <br>
          </td>
          <td style="width: 29%; vertical-align: middle; text-align: center; padding-bottom: 2px;">&#160;</td>
        </tr>
        <tr>
          <td style="vertical-align: middle;" colspan="4" rowspan="1">&#160;&#160;</td>
        </tr>
        <tr>
          <td style="width: 29%; vertical-align: top; padding-bottom: 2px;"><br>
          </td>
          <td style="width: 6%; vertical-align: bottom; padding-bottom: 2px;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">By:</font></div>
          </td>
          <td style="width: 36%; vertical-align: top; border-bottom: 2px solid rgb(0, 0, 0);">
            <div>
              <div><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">/s/ Scott D. Beamer</font> <br>
              </div>
            </div>
          </td>
          <td style="width: 29%; vertical-align: top; padding-bottom: 2px;">&#160;</td>
        </tr>
        <tr>
          <td style="width: 29%; vertical-align: top;">&#160;</td>
          <td style="width: 6%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 36%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Scott D. Beamer</font></div>
          </td>
          <td style="width: 29%; vertical-align: top;">&#160;</td>
        </tr>
        <tr>
          <td style="width: 29%; vertical-align: top;">&#160;</td>
          <td style="width: 6%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 36%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;"><font style="background-color: #FFFFFF; font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Vice President and Chief
                  Financial Officer&#160;</font></font></div>
          </td>
          <td style="width: 29%; vertical-align: top;">&#160;</td>
        </tr>

    </table>
    <div style="background-color: #FFFFFF;">
      <div><br>
      </div>
      <div style="clear: both; margin-top: 10pt; margin-bottom: 10pt;" id="DSPFPageBreakArea">
        <div style="page-break-after: always;" id="DSPFPageBreak">
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      </div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">POWER OF ATTORNEY</font></div>
      <div><br>
      </div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Each of the undersigned directors and/or officers of the registrant whose individual signature appears below hereby appoints David H. Li,
          Scott. D. Beamer and H. Carol Bernstein, and each of them, any of whom may act without the joinder of the others, as the true and lawful attorney-in-fact and agent of the undersigned, in any and all capacities, with full power of substitution, to
          sign any and all amendments to this registration statement (including post-effective amendments), and, in connection with any registration of additional securities, to sign any abbreviated registration statement and any and all amendments
          thereto, and to file the same with exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact, and each of them, full power and authority to do and perform each
          and every act and thing requisite and necessary to be done, as fully to all intents and purposes as the undersigned might or could do in person, hereby ratifying and confirming all that each said attorney-in-fact and agent, or his substitute or
          substitutes, may lawfully do or cause to be done by virtue hereof.</font></div>
      <div><br>
      </div>
      <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed below by the following persons in the
          capacities and on the dates indicated.</font></div>
    </div>
    <div style="background-color: #FFFFFF;">
      <div><br>
      </div>
    </div>
    <table cellspacing="0" cellpadding="0" id="z89e0d3dd72e148bca40ace47c8d367fc" style="font-family: 'Times New Roman', Times, serif; font-size: 10pt; width: 100%;">

        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">SIGNATURE</font></div>
          </td>
          <td style="width: 40.96%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">TITLE</font></div>
          </td>
          <td style="width: 25.7%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">DATE</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">&#160;</td>
          <td style="width: 40.96%; vertical-align: bottom;">&#160;</td>
          <td style="width: 25.7%; vertical-align: bottom;">&#160;</td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">&#160;</td>
          <td style="width: 40.96%; vertical-align: bottom;">&#160;</td>
          <td style="width: 25.7%; vertical-align: bottom;">&#160;</td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom; border-bottom: #000000 2px solid;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">/s/ William P. Noglows*</font></div>
          </td>
          <td style="width: 40.96%; vertical-align: bottom;" rowspan="2">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Chairman of the Board</font></div>
            <div>&#160;</div>
          </td>
          <td style="width: 25.7%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">June 12, 2019</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">William P. Noglows</font></div>
          </td>
          <td style="width: 25.7%; vertical-align: bottom;">&#160;</td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">&#160;</td>
          <td style="width: 40.96%; vertical-align: bottom;">&#160;</td>
          <td style="width: 25.7%; vertical-align: bottom;">&#160;</td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom; border-bottom: #000000 2px solid;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">/s/ David H. Li</font></div>
          </td>
          <td style="width: 40.96%; vertical-align: bottom;" rowspan="2">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Director, President and Chief Executive Officer (Principal Executive Officer)</font></div>
          </td>
          <td style="width: 25.7%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">June 12, 2019</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">David H. Li</font></div>
          </td>
          <td style="width: 25.7%; vertical-align: bottom;">&#160;</td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">&#160;</td>
          <td style="width: 40.96%; vertical-align: bottom;">&#160;</td>
          <td style="width: 25.7%; vertical-align: bottom;">&#160;</td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom; border-bottom: #000000 2px solid;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">/s/ Richard S. Hill*</font></div>
          </td>
          <td style="width: 40.96%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Director</font></div>
          </td>
          <td style="width: 25.7%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">June 12, 2019</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Richard S. Hill</font></div>
          </td>
          <td style="width: 40.96%; vertical-align: bottom;">&#160;</td>
          <td style="width: 25.7%; vertical-align: bottom;">&#160;</td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">&#160;</td>
          <td style="width: 40.96%; vertical-align: bottom;">&#160;</td>
          <td style="width: 25.7%; vertical-align: bottom;">&#160;</td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom; border-bottom: #000000 2px solid;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">/s/ Barbara A. Klein*</font></div>
          </td>
          <td style="width: 40.96%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Director</font></div>
          </td>
          <td style="width: 25.7%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">June 12, 2019</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Barbara A. Klein</font></div>
          </td>
          <td style="width: 40.96%; vertical-align: bottom;">&#160;</td>
          <td style="width: 25.7%; vertical-align: bottom;">&#160;</td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">&#160;</td>
          <td style="width: 40.96%; vertical-align: bottom;">&#160;</td>
          <td style="width: 25.7%; vertical-align: bottom;">&#160;</td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom; border-bottom: #000000 2px solid;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">/s/ Paul J. Reilly*</font></div>
          </td>
          <td style="width: 40.96%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Director</font></div>
          </td>
          <td style="width: 25.7%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">June 12, 2019</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Paul J. Reilly</font></div>
          </td>
          <td style="width: 40.96%; vertical-align: bottom;">&#160;</td>
          <td style="width: 25.7%; vertical-align: bottom;">&#160;</td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">&#160;</td>
          <td style="width: 40.96%; vertical-align: bottom;">&#160;</td>
          <td style="width: 25.7%; vertical-align: bottom;">&#160;</td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom; border-bottom: #000000 2px solid;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">/s/ Susan M. Whitney*</font></div>
          </td>
          <td style="width: 40.96%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Director</font></div>
          </td>
          <td style="width: 25.7%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">June 12, 2019</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Susan M. Whitney</font></div>
          </td>
          <td style="width: 40.96%; vertical-align: bottom;">&#160;</td>
          <td style="width: 25.7%; vertical-align: bottom;">&#160;</td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">&#160;</td>
          <td style="width: 40.96%; vertical-align: bottom;">&#160;</td>
          <td style="width: 25.7%; vertical-align: bottom;">&#160;</td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom; border-bottom: #000000 2px solid;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">/s/ Geoffrey Wild*</font></div>
          </td>
          <td style="width: 40.96%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Director</font></div>
          </td>
          <td style="width: 25.7%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">June 12, 2019</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Geoffrey Wild</font></div>
          </td>
          <td style="width: 40.96%; vertical-align: bottom;">&#160;</td>
          <td style="width: 25.7%; vertical-align: bottom;">&#160;</td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">&#160;</td>
          <td style="width: 40.96%; vertical-align: bottom;">&#160;</td>
          <td style="width: 25.7%; vertical-align: bottom;">&#160;</td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom; border-bottom: #000000 2px solid;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">/s/ Scott D. Beamer*</font></div>
          </td>
          <td style="width: 40.96%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;"><font style="background-color: #FFFFFF; font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Vice President and Chief
                  Financial Officer (Principal Financial Officer)</font></font></div>
          </td>
          <td style="width: 25.7%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">June 12, 2019</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Scott D. Beamer</font></div>
          </td>
          <td style="width: 40.96%; vertical-align: bottom;">&#160;</td>
          <td style="width: 25.7%; vertical-align: bottom;">&#160;</td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">&#160;</td>
          <td style="width: 40.96%; vertical-align: bottom;">&#160;</td>
          <td style="width: 25.7%; vertical-align: bottom;">&#160;</td>
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        <tr>
          <td style="width: 33.33%; vertical-align: bottom; border-bottom: #000000 2px solid;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">/s/ Thomas S. Roman</font></div>
          </td>
          <td style="width: 40.96%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Principal Accounting Officer and Corporate Controller (Principal Accounting Officer)</font></div>
          </td>
          <td style="width: 25.7%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">June 12, 2019</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 33.33%; vertical-align: bottom;">
            <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Thomas S. Roman</font></div>
          </td>
          <td style="width: 40.96%; vertical-align: bottom;">&#160;</td>
          <td style="width: 25.7%; vertical-align: bottom;">&#160;</td>
        </tr>

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    <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">*<font style="font-family: 'Times New Roman', serif; font-size: 1pt;">&#160;</font>by H. Carol Bernstein as Attorney-in-fact</font></div>
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      <div style="text-align: center;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">INDEX TO EXHIBITS</font></div>
      <div><br>
      </div>
    </div>
    <table cellspacing="0" cellpadding="0" id="z2efd865c223c436d935da631c2cc5486" style="font-family: 'Times New Roman', Times, serif; font-size: 10pt; width: 100%;">

        <tr>
          <td style="width: 10.24%; vertical-align: bottom; border-bottom: #000000 2px solid;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">EXHIBIT </font></div>
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">NO.</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: bottom; border-bottom: #000000 2px solid;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif; font-weight: bold;">DESCRIPTION</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">3.1</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">(Third) Amended and Restated By-Laws of Cabot Microelectronics Corporation (incorporated by reference to Exhibit 3.2 to the Registrant&#8217;s
                Current Report on Form&#160;8-K filed with the Commission on March 7, 2017).</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">3.2</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Form of Amended and Restated Certificate of Incorporation of Cabot Microelectronics Corporation (incorporated by reference to
                Exhibit&#160;3.3 to the Registrant&#8217;s Registration Statement on Form&#160;S-1 (No.&#160;333-95093) filed with the Commission on March&#160;27, 2000).</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">4.1</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Form of Cabot Microelectronics Corporation Common Stock Certificate (incorporated by reference to Exhibit&#160;4.1 to the Registrant&#8217;s
                Registration Statement on Form&#160;S-1 (No.&#160;333-95093) filed with the Commission on April&#160;3, 2000).</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">4.2</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Cabot Microelectronics Corporation 2012 Omnibus Incentive
                  Plan, as amended effective March 7, 2017 (incorporated by </font>reference to Exhibit&#160;10.61 to the Registrant&#8217;s Quarterly Report on Form&#160;10-Q filed with the Commission on May 5, 2017).</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">5.1</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Opinion of Wachtell, Lipton, Rosen &amp; Katz.</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">23.1</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Consent of Wachtell, Lipton, Rosen &amp; Katz (included in Exhibit&#160;5.1).</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">23.2</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Consent of PricewaterhouseCoopers LLP (Independent Registered Public Accounting Firm).</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div>&#160;</div>
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">23.3</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div>&#160;</div>
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Consent of KPMG, LLP (Independent Registered Public Accounting Firm).</font></div>
          </td>
        </tr>
        <tr>
          <td style="width: 10.24%; vertical-align: top;">
            <div>&#160;</div>
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">24.1</font></div>
          </td>
          <td style="width: 0.2%; vertical-align: bottom;">
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">&#160;</font></div>
          </td>
          <td style="width: 89.57%; vertical-align: top;">
            <div>&#160;</div>
            <div style="text-align: left;"><font style="font-size: 10pt; font-family: 'Times New Roman', Times, serif;">Power of Attorney (included in the signature page to this Registration Statement).</font></div>
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{"company-data": {"conformed-name": "CABOT MICROELECTRONICS CORP", "cik": "0001102934", "assigned-sic": "3674", "irs-number": "364324765", "state-of-incorporation": "DE", "fiscal-year-end": "0930"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-232088", "film-number": "19894803"}, "business-address": {"street1": "870 NORTH COMMONS DRIVE", "city": "AURORA", "state": "IL", "zip": "60504", "phone": "6303755461"}, "mail-address": {"street1": "870 N COMMONS DR", "city": "AURORA", "state": "IL", "zip": "60504"}}
As filed with the Securities and Exchange Commission on June 12, 2019
Registration No. 33
3
-
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM S-8
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933
CABOT MICROELECTRONICS CORPORATION
(Exact name of registrant as specified in its charter)
Delaware
36-4324765
(State of Incorporation)
(IRS Employer
Identification No.)
870 North Commons Drive
Aurora, Illinois 60504
(630) 375-6631
(Address, including Zip Code, and Telephone Number, Including Area Code, of Registrant's Principal Executive Offices)
Cabot Microelectronics Corporation 2012 Omnibus Incentive Plan (as amended)
(Full Title of the Plan)
H. Carol Bernstein
Vice President, Secretary and General Counsel
870 North Commons Drive
Aurora, Illinois 60504
(630) 375-5461
(Name, Address, including Zip Code, and Telephone Number, including Area Code, of Agent for Service)
Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a
        smaller reporting company, or an emerging growth company. See the definitions of "large accelerated filer," "accelerated filer," "smaller reporting company," and "emerging growth company" in Rule 12b-2 of the Exchange Act.
Large accelerated filer
☒
Accelerated filer
☐
Non-accelerated filer
☐
(Do not check if a smaller reporting company)
Smaller reporting company
☐
Emerging growth company
☐
If an emerging growth company,
            indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.
☐
CALCULATION OF REGISTRATION FEE
Title of Securities to
be Registered)
Amount to be
Registered (1)(2)
Proposed Maximum
Offering Price per Share (3)
Proposed Maximum
Aggregate Offering
Price (4)
Amount of
Registration Fee (2)
Common Stock par value $.001 per share
43,443.00
$104.99
$4,561,080.57
$552.80
(1)
Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the "Securities Act"), this Registration Statement shall also
                cover any additional shares of
Cabot Microelectronics Corporation ("Cabot Microelectronics") common stock,
par value $0.001 per share ("CMC Common Stock"),
which become issuable under
                the Cabot Microelectronics Corporation 2012 Omnibus Incentive Plan, as amended (the "Plan") by reason of any stock dividend, stock split, recapitalization or any other similar transaction effected without the receipt of consideration which
                results in an increase in the number of CMC Common Stock.
(2)
Represents the
number of shares
                  of CMC Common Stock
reserved for issuance
as a result of the conversion of
restricted stock unit awards relating to shares of common stock of KMG Chemicals, Inc. ("KMG"), par value $0.01 per share ("KMG Common Stock"), (each, a "KMG Equity Award")
granted on or following August 14, 2018
and outstanding as of
immediately prior to the effective time of the merger into restricted stock unit awards relating to shares of CMC Common Stock.
(3)
Estimated solely for the purpose of determining the registration fee pursuant to Rules 457(c) and 457(h) of the Securities Act and based
                on the average of the high and low prices of a share of CMC Common Stock as reported on the NASDAQ Global Select Market on June 7, 2019.
(4)
This Registration Statement registers additional shares of CMC Common Stock issuable pursuant to the same employee benefit plan for
                which Registration Statement No. 333-179955 is currently effective. Accordingly, pursuant to Instruction E on Form S-8, the registration fee is being paid with respect to the additional securities only.
EXPLANATORY NOTE
Pursuant to the Agreement and Plan of Merger,
          dated as of August 14, 2018 (the "merger agreement"), by and among Cabot Microelectronics, KMG and Cobalt Merger Sub Corporation, a Texas corporation and a wholly owned subsidiary of Cabot Microelectronics ("Merger Sub"), Merger Sub merged with
          and into KMG, with KMG becoming a direct, wholly owned subsidiary of Cabot Microelectronics (the "merger"). In connection with the merger, and as of the effective time of the merger (the "Effective Time"), each KMG Equity Award
granted on or following August 14, 2018 was converted into a corresponding award relating
          to shares of CMC Common Stock subject to the terms of the applicable award agreement. Section 6.6 of the Plan permits Cabot Microelectronics to grant awards to person who became employees, directors or advisors in connection with the merger for
          equity incentives held by them in KMG.
This registration statement has been filed for the purpose of registering CMC Common Stock issuable upon the exercise of
          such awards.
Pursuant to General Instruction E of Form S-8, the contents of Registration Statement No. 333-
179955
are incorporated herein by reference, to the extent not amended hereby.
PART I
INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS
We shall send or give to each participant in the Plan the document(s) containing the information specified in Part I of
          Form S-8 as specified by Rule 428(b)(1) of the Securities Act. In accordance with the rules and regulations of the Securities and Exchange Commission (the "Commission"), such documents are not being filed with or included in this Registration
          Statement. These documents, and the documents incorporated by reference into this Registration Statement pursuant to Item 3 of Part II of this Registration Statement, taken together, constitute a prospectus that meets the requirements of Section
          10(a) of the Securities Act.
PART II
INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
Item 3. Incorporation of Documents by Reference.
We have filed with the Commission and hereby incorporate by reference the following documents:
(a)
Our Annual Report on Form 10-K for the fiscal year ended September 30, 2018 filed with the Commission on November 13, 2018;
(b)
Our Quarterly Reports on Form 10-Q for the quarter ended December 31, 2018 filed with the Commission on February 11, 2019 and for
                    the quarter ended March 31, 2019 filed with the Commission on May 10, 2019;
(c)
Current Reports on Form 8-K filed on November 15, 2018 (as amended by the Form 8-K/A filed on January 31, 2019), December 7, 2018,
                    January 24, 2019, March 6, 2019 and March 7, 2019 (excluding any information furnished under Items 2.02, 7.01 and 9.01 thereof); and
(d)
The description of CMC Common Stock contained in our Registration Statement on Form 8-A filed with the Commission on April 3, 2000.
In addition, all documents subsequently filed pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Securities Exchange
          Act of 1934, as amended, (the "Exchange Act"), prior to the filing of a post-effective amendment which indicates that all shares of CMC Common Stock subject to the Plan have been sold or which deregisters all of such shares then remaining unsold,
          shall be deemed to be incorporated by reference into this Registration Statement and to be a part hereof from the date of filing of such documents. Notwithstanding the foregoing, unless specifically stated to the contrary, none of the information
          disclosed by us under Items 2.02 or 7.01 of any current report on Form 8-K that we may from time to time furnish to the Commission will be incorporated by reference into, or otherwise included in, this Registration Statement. Any statement
          contained herein or in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded for purposes of this Registration Statement to the extent that a statement contained herein or in any
          subsequently filed document which also is or is deemed to be incorporated by reference herein modifies or supersedes such statement. Any such statement so modified or superseded shall not be deemed, except as so modified or superseded, to
          constitute a part of this Registration Statement.
Item 4. Description of Securities.
Not Applicable.
Item 5. Interests of Named Experts and Counsel.
Not Applicable.
Item 6. Indemnification of Directors and Officers.
Section 145 of the Delaware General Corporation Law (the "DGCL") provides that a corporation may indemnify directors and
          officers as well as other employees and individuals against expenses (including attorneys' fees), judgments, fines and amounts paid in settlement in connection with specified actions, suits and proceedings, whether civil, criminal,
          administrative, or investigative (other than an action by or in the right of the corporation – a "derivative action"), if they acted in good faith and in a manner they reasonably believed to be in or not opposed to the best interests of the
          corporation and, with respect to any criminal action or proceeding, had no reasonable cause to believe their conduct was unlawful. A similar standard is applicable in the case of derivative actions, except that indemnification only extends to
          expenses (including attorneys' fees) incurred in connection with the defense or settlement of such action, and the statute requires court approval before there can be any indemnification where the person seeking indemnification has been found
          liable to the corporation. The statute provides that it is not exclusive of other indemnification that may be granted by a corporation's certificate of incorporation, bylaws, disinterested director vote, stockholder vote, agreement, or otherwise.
Our bylaws and our certificate of incorporation require us to indemnify to the fullest extent authorized by the DGCL any
          person made or threatened to be made a party to an action, suit or proceeding, whether criminal, civil, administrative or investigative, by reason of the fact that he or she is or was a director or officer of Cabot Microelectronics, or is or was
          serving at the request of Cabot Microelectronics as a director, officer, employee or agent of another corporation or of a partnership, joint venture, trust or other enterprise.
As permitted by section 102(b)(7) of the DGCL, our certificate of incorporation eliminates the liability of a director to
          the corporation or its stockholders for monetary damages for such breach of fiduciary duty as a director, except for liabilities arising (a) from any breach of the director's duty of loyalty to the corporation or its stockholders; (b) from acts
          or omissions not in good faith or which involve intentional misconduct or a knowing violation of law; (c) under section 174 of the DGCL; or (d) from any transaction from which the director derived an improper personal benefit.
We maintain primary and excess insurance policies insuring our directors and officers and those of our subsidiaries against
          certain liabilities they may incur in their capacity as directors and officers. Under these policies, the insurer, on our behalf, may also pay amounts for which we have granted indemnification to the directors or officers.
Item 7. Exemption from Registration Claimed.
Not Applicable.
Item 8. Exhibits.
EXHIBIT
NO.
DESCRIPTION
3.1
(Third) Amended and Restated By-Laws of Cabot Microelectronics Corporation (incorporated by reference to Exhibit 3.2 to the Registrant's
                Current Report on Form 8-K filed with the Commission on March 7, 2017).
3.2
Form of Amended and Restated Certificate of Incorporation of Cabot Microelectronics Corporation (incorporated by reference to
                Exhibit 3.3 to the Registrant's Registration Statement on Form S-1 (No. 333-95093) filed with the Commission on March 27, 2000).
4.1
Form of Cabot Microelectronics Corporation Common Stock Certificate (incorporated by reference to Exhibit 4.1 to the Registrant's
                Registration Statement on Form S-1 (No. 333-95093) filed with the Commission on April 3, 2000).
4.2
Cabot Microelectronics Corporation 2012 Omnibus Incentive
                  Plan, as amended effective March 7, 2017 (incorporated by
reference to Exhibit 10.61 to the Registrant's Quarterly Report on Form 10-Q filed with the Commission on May 5, 2017).
5.1
Opinion of Wachtell, Lipton, Rosen & Katz.
23.1
Consent of Wachtell, Lipton, Rosen & Katz (included in Exhibit 5.1).
23.2
Consent of PricewaterhouseCoopers LLP (Independent Registered Public Accounting Firm).
23.3
Consent of KPMG, LLP (Independent Registered Public Accounting Firm).
24.1
Power of Attorney (included in the signature page to this Registration Statement).
Item 9. Undertakings.
(a) The Registrant hereby undertakes:
(1) To file, during any period in which offers or sales are being made, a post-effective amendment to this registration
        statement:
(i) To include any prospectus required by Section 10(a)(3) of the Securities Act.
(ii) To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the
        most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of
        securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with
        the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20% change in the maximum aggregate offering price set forth in the "Calculation of Registration Fee" table in the effective
        registration statement.
(iii) To include any material information with respect to the plan of distribution not previously disclosed in the
        registration statement or any material change to such information in the registration statement;
Provided, however
,
        that paragraphs (a)(1)(i) and (a)(1)(ii) herein do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the Commission by the Registrant pursuant
        to Section 13 or Section 15(d) of the Exchange Act (15 U.S.C. 78m or 78o(d)) that are incorporated by reference in the registration statement.
(2) That, for the purpose of determining any liability under the Securities Act, each such post-effective amendment shall be
        deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.
(3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain
        unsold at the termination of the offering.
(b) The Registrant hereby undertakes that, for purposes of determining any liability under the Securities Act, each filing of
        the Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the Exchange Act (and, where applicable, each filing of an employee benefit plan's annual report pursuant to Section 15(d) of the Exchange Act) that is incorporated by
        reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.
(c) Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers and
        controlling persons of the Registrant pursuant to the foregoing provisions, or otherwise, the Registrant has been advised that in the opinion of the Commission such indemnification is against public policy as expressed in the Securities Act and is,
        therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the Registrant of expenses incurred or paid by a director, officer or controlling person of the Registrant in the successful
        defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the Registrant will, unless in the opinion of its counsel the matter has been settled by
        controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act and will be governed by the final adjudication of such issue.
SIGNATURES
Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable
        grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Aurora, State of Illinois, on
        June 12, 2019.
CABOT MICROELECTRONICS CORPORATION
By:
/s/ Scott D. Beamer
Scott D. Beamer
Vice President and Chief
                  Financial Officer
POWER OF ATTORNEY
Each of the undersigned directors and/or officers of the registrant whose individual signature appears below hereby appoints David H. Li,
          Scott. D. Beamer and H. Carol Bernstein, and each of them, any of whom may act without the joinder of the others, as the true and lawful attorney-in-fact and agent of the undersigned, in any and all capacities, with full power of substitution, to
          sign any and all amendments to this registration statement (including post-effective amendments), and, in connection with any registration of additional securities, to sign any abbreviated registration statement and any and all amendments
          thereto, and to file the same with exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact, and each of them, full power and authority to do and perform each
          and every act and thing requisite and necessary to be done, as fully to all intents and purposes as the undersigned might or could do in person, hereby ratifying and confirming all that each said attorney-in-fact and agent, or his substitute or
          substitutes, may lawfully do or cause to be done by virtue hereof.
Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed below by the following persons in the
          capacities and on the dates indicated.
SIGNATURE
TITLE
DATE
/s/ William P. Noglows*
Chairman of the Board
June 12, 2019
William P. Noglows
/s/ David H. Li
Director, President and Chief Executive Officer (Principal Executive Officer)
June 12, 2019
David H. Li
/s/ Richard S. Hill*
Director
June 12, 2019
Richard S. Hill
/s/ Barbara A. Klein*
Director
June 12, 2019
Barbara A. Klein
/s/ Paul J. Reilly*
Director
June 12, 2019
Paul J. Reilly
/s/ Susan M. Whitney*
Director
June 12, 2019
Susan M. Whitney
/s/ Geoffrey Wild*
Director
June 12, 2019
Geoffrey Wild
/s/ Scott D. Beamer*
Vice President and Chief
                  Financial Officer (Principal Financial Officer)
June 12, 2019
Scott D. Beamer
/s/ Thomas S. Roman
Principal Accounting Officer and Corporate Controller (Principal Accounting Officer)
June 12, 2019
Thomas S. Roman
*
by H. Carol Bernstein as Attorney-in-fact
INDEX TO EXHIBITS
EXHIBIT
NO.
DESCRIPTION
3.1
(Third) Amended and Restated By-Laws of Cabot Microelectronics Corporation (incorporated by reference to Exhibit 3.2 to the Registrant's
                Current Report on Form 8-K filed with the Commission on March 7, 2017).
3.2
Form of Amended and Restated Certificate of Incorporation of Cabot Microelectronics Corporation (incorporated by reference to
                Exhibit 3.3 to the Registrant's Registration Statement on Form S-1 (No. 333-95093) filed with the Commission on March 27, 2000).
4.1
Form of Cabot Microelectronics Corporation Common Stock Certificate (incorporated by reference to Exhibit 4.1 to the Registrant's
                Registration Statement on Form S-1 (No. 333-95093) filed with the Commission on April 3, 2000).
4.2
Cabot Microelectronics Corporation 2012 Omnibus Incentive
                  Plan, as amended effective March 7, 2017 (incorporated by
reference to Exhibit 10.61 to the Registrant's Quarterly Report on Form 10-Q filed with the Commission on May 5, 2017).
5.1
Opinion of Wachtell, Lipton, Rosen & Katz.
23.1
Consent of Wachtell, Lipton, Rosen & Katz (included in Exhibit 5.1).
23.2
Consent of PricewaterhouseCoopers LLP (Independent Registered Public Accounting Firm).
23.3
Consent of KPMG, LLP (Independent Registered Public Accounting Firm).
24.1
Power of Attorney (included in the signature page to this Registration Statement).