<PAGE>

      As filed with the Securities and Exchange Commission on May 4, 2000
                                                     Registration  No. 333-_____

================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                -----------------

                                    FORM S-8
             REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

                                -----------------

                               INPUT/OUTPUT, INC.
             (Exact name of registrant as specified in its charter)

               DELAWARE                                     22-2286646
     (State or other jurisdiction                        (I.R.S. Employer
   of incorporation or organization)                  Identification Number)

                          11104 WEST AIRPORT BOULEVARD
                              STAFFORD, TEXAS 77477
                                 (281) 933-3339
       (Address, including zip code, and telephone number, including area
                code, of registrant's principal executive offices)

                                -----------------

                  INPUT/OUTPUT, INC. 2000 RESTRICTED STOCK PLAN
                              (Full Title of Plan)

                              C. ROBERT BUNCH, ESQ.
                               INPUT/OUTPUT, INC.
                          11104 WEST AIRPORT BOULEVARD
                              STAFFORD, TEXAS 77477
                                 (281) 933-3339
       (Name, address, including zip code, and telephone number, including
                        area code, of agent for service)

                                 WITH COPIES TO:
                            HAYNES AND BOONE, L.L.P.
                           1000 LOUISIANA, SUITE 4300
                              HOUSTON, TEXAS 77002
                             ATTN: MARC H. FOLLADORI
                                 (713) 547-2000

                                -----------------

                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
=========================================================================================================================
                                                                      PROPOSED
                                                                      MAXIMUM         PROPOSED MAXIMUM       AMOUNT OF
                 TITLE OF                       AMOUNT TO BE       OFFERING PRICE    AGGREGATE OFFERING    REGISTRATION
        SECURITIES TO BE REGISTERED           REGISTERED(1)(2)      PER SHARE(2)          PRICE(2)              FEE
-------------------------------------------------------------------------------------------------------------------------
<S>                                           <C>                  <C>               <C>                   <C>
Common Stock, par value $0.01 per share            200,000             $8.0625          $1,612,500.00         $425.70
=========================================================================================================================
</TABLE>

(1)  Pursuant to Rule 416(c), also registered hereunder is an indeterminate
     number of shares of Common Stock issuable as a result of the anti-dilution
     provisions of the Input/Output, Inc. 2000 Restricted Stock Plan (the
     "Plan").

(2)  The 200,000 shares registered hereby represent shares issuable pursuant to
     the Plan. With respect to the shares registered hereby, the offering price
     per share, the aggregate offering price and the registration fee have been
     calculated in accordance with paragraphs (c) and (h)(1) of Rule 457 on the
     basis of the average high and low sale prices for the Company's Common
     Stock on May 2, 2000 as reported on the New York Stock Exchange composite
     tape ($8.0625 per share).

<PAGE>


                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE.

         The contents of the following documents filed by Input/Output, Inc., a
Delaware corporation (the "Company"), with the Securities and Exchange
Commission (the "Commission") are incorporated into this registration statement
(this "Registration Statement") by reference:

         (a) The Company's Annual Report, dated August 20, 1999, as filed with
the Commission on Form 10-K, File No. 1-12691, for the fiscal year ended May 31,
1999;

         (b) All other reports filed pursuant to Section 13(a) or 15(d) of the
Securities Exchange Act of 1934, as amended (the "Exchange Act"), since May 31,
1999;

         (c) The description of the Company's common stock, par value $0.01 per
share (the "Common Stock"), contained in the Company's Registration Statement on
Form 8-A filed under Section 12(b) of the Exchange Act, dated October 17, 1994;
and

         (d) The description of the Company's rights to purchase Series A
Preferred Stock, par value $0.01 per share, contained in the Company's
Registration Statement on Form 8-A filed under Section 12(b) of the Exchange
Act, dated January 27, 1997.

         All documents filed by the Company with the Commission pursuant to
Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act subsequent to the filing
date of this Registration Statement and prior to the filing of a post-effective
amendment to this Registration Statement which indicates that all securities
offered have been sold or which deregisters all securities then remaining unsold
shall be deemed to be incorporated by reference in this Registration Statement
and to be a part hereof from the date of filing such documents.

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 permits a
corporation to indemnify any person who was or is a party or is threatened to be
made a party to any threatened, pending or completed action, suit or proceeding,
whether civil, criminal, administrative or investigative, by reason of the fact
that he is or was a director, officer, employee or agent of the corporation or
is or was serving at the request of the corporation as a director, officer,
employee or agent of another corporation, partnership, joint venture, trust or
other enterprise, against expenses (including attorney's fees), judgments, fines
and amounts paid in settlement actually and reasonably incurred by the person in
connection with such action, suit or proceeding.

         In an action brought to obtain a judgment in the corporation's favor,
whether by the corporation itself or derivatively by a stockholder, the
corporation may only indemnify for expenses, including attorney's fees, actually
and reasonably incurred in connection with the defense or settlement of such
action, and the corporation may not indemnify for amounts paid in satisfaction
of a judgment or in settlement of the claim. In any such action, no
indemnification may be paid in respect of any claim, issue or matter as to
which such person shall have been adjudged liable to the corporation except
as otherwise approved by the Delaware Court of Chancery or the court in which
the claim was brought. In any other


                                     -2-
<PAGE>


type of proceeding, the indemnification may extend to judgments, fines and
amounts paid in settlement, actually and reasonably incurred in connection with
such other proceeding, as well as to expenses.

         The statute does not permit indemnification unless the person seeking
indemnification has acted in good faith and in a manner reasonably believed to
be in, or not opposed to, the best interests of the corporation and, in the case
of criminal actions or proceedings, the person had no reasonable cause to
believe his conduct was unlawful. The statute contains additional limitations
applicable to criminal actions and to actions brought by or in the name of the
corporation. The determination as to whether a person seeking indemnification
has met the required standard of conduct is to be made by the corporation only
as authorized in the specific case upon a determination that indemnification of
such person is proper in the circumstances. The determination as to whether a
person who is a director or officer at the time of such determination has met
the required standard of conduct is to be made (1) by a majority vote of the
disinterested directors, even though less than a quorum, (2) by a committee of
such directors designated by a majority vote of such directors, even though less
than a quorum, (3) if there are no disinterested directors or if the
disinterested directors so direct, by independent legal counsel in a written
opinion, or (4) by the stockholders.

         The Company's Bylaws require the Company to indemnify its directors,
officers, employees, and agents to the fullest extent permitted under Delaware
law. The Company's Certificate of Incorporation provides that a director of the
corporation shall not be held personally liable to the corporation or its
shareholders for monetary damages for breach of a director's fiduciary duty of
care, except that a director shall continue to be held personally liable for (i)
breach of the duty of loyalty, (ii) failure to act in good faith, (iii) engaging
in intentional misconduct or knowingly violating a law, (iv) paying a dividend
or approving a stock repurchase which was illegal under Delaware law, or (v)
obtaining an improper personal benefit.

         The Company has purchased insurance on behalf of its directors and
officers against certain liabilities that may be asserted against, or incurred
by, such persons in their capacities as directors or officers of the registrant,
or that may arise out of their status as directors or officers of the
registrant, including liabilities under the federal and state securities laws.

ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED.

         Not applicable.

ITEM 8. EXHIBITS.


Exhibit                           Description
-------                           -----------

  4.1     Amended and Restated Certificate of Incorporation, filed as
          Exhibit 3.1 to the Company's Annual Report on Form 10-K for the
          fiscal year ended May 31, 1995, is incorporated herein by reference.

  4.2     Certificate of Amendment to the Amended and Restated Certificate of
          Incorporation, dated October 11, 1996, filed as Exhibit 3.2 to the
          Company's Annual Report on Form 10-K for the fiscal year ended May 31,
          1997, is incorporated herein by reference.

  4.3     Amended and Restated Bylaws, filed as Exhibit 3.2 to the Company's
          Annual Report on Form 10-K for the fiscal year ended May 31, 1995,
          is incorporated herein by reference.

  4.4     Specimen certificate for shares of the Company's common stock, par
          value $0.01 per share, filed as Exhibit F to the Company's
          Registration Statement on Form 8-A dated October 17, 1994, is
          incorporated herein by reference.


                                     -3-
<PAGE>


Exhibit                           Description
-------                           -----------

   4.5    Rights Agreement, dated as of January 17, 1997, by and between the
          Company and Harris Trust and Savings Bank, as Rights Agent, including
          exhibits thereto, filed as Exhibit 1 to the Company's Registration
          Statement on Form 8-A dated January 27, 1997, is incorporated herein
          by reference.

   4.6    Form of rights certificate to purchase Series A Preferred Stock, par
          value $0.01 per share, filed as Exhibit 3 to the Company's
          Registration Statement on Form 8-A dated January 27, 1997, is
          incorporated herein by reference.

   4.7    The Company's 2000 Restricted Stock Plan.

   5.1    Opinion of Haynes and Boone, L.L.P.

  23.1    Consent of KPMG LLP.

  23.2    Consent of Haynes and Boone, L.L.P. (included in Exhibit
          5.1 opinion).

  24.1    Power of Attorney (included on the signature page hereto).


ITEM 9.   UNDERTAKINGS.

          A.   UNDERTAKING TO UPDATE

               The undersigned 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 of 1933;

                   (ii)  To reflect in the prospectus any facts or events
               arising after the effective date of this 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 this Registration Statement; and

                   (iii) To include any material information with respect to
               the plan of distribution not previously disclosed in this
               Registration Statement or any material change to such information
               in this Registration Statement;

          PROVIDED, HOWEVER, that paragraphs (a)(1)(i) and (a)(1)(ii) do not
          apply if the information required to be included in a post-effective
          amendment by those paragraphs is contained in periodic reports
          filed with or furnished to the Commission by the registrant
          pursuant to Section 13 or Section 15(d) of the Exchange Act that
          are incorporated by reference in this Registration Statement.

               (2) That, for the purpose of determining any liability under
          the Securities Act of 1933, 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.


                                     -4-
<PAGE>


               (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.   UNDERTAKING WITH RESPECT TO DOCUMENTS INCORPORATED BY REFERENCE

               The undersigned registrant hereby undertakes that, for
               purposes of determining any liability under the Securities Act
               of 1933, each filing of the registrant's annual report pursuant
               to Section 13(a) or 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.   UNDERTAKING WITH RESPECT TO INDEMNIFICATION

               Insofar as indemnification for liabilities arising under the
               Securities Act of 1933 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
               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 Act and will be governed by the final adjudication of such
               issue.


                                     -5-
<PAGE>

                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, the
Registrant certifies that it has reasonable grounds to believe that it meets all
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 Stafford, State of Texas, on April 27, 2000.

                                     INPUT/OUTPUT, INC.

                                     By: /s/ C. ROBERT BUNCH
                                        ---------------------------------------
                                           C. Robert Bunch
                                           Vice President, Chief Administrative
                                           Officer and Secretary
                                           (Principal Financial Officer)

                                POWER OF ATTORNEY

         Each of the undersigned hereby appoints Tim Probert and C. Robert
Bunch, and each of them (with full power to act alone), as attorney and agents
for the undersigned, with full power of substitution, for and in the name, place
and stead of the undersigned, to sign and file with the Securities and Exchange
Commission under the Securities Act of 1933 any and all amendments and exhibits
to this Registration Statement and any and all applications, instruments and
other documents to be filed with the Securities and Exchange Commission
pertaining to the registration of the securities covered hereby, with full power
and authority to do and perform any and all acts and things whatsoever requisite
or desirable.

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities indicated on April 27, 2000.

<TABLE>
<CAPTION>
         SIGNATURE                                       TITLE
         ---------                                       -----
<S>                                    <C>
/s/ TIM PROBERT                        Director, President and Chief Executive
-------------------------------        Officer (Principal Executive Officer)
    Tim Probert

/s/ C. ROBERT BUNCH                    Vice President, Chief Administrative
-------------------------------        Officer and Secretary
    C. Robert Bunch                    (Principal Financial Officer)

/s/ JAMES M. LAPEYRE, JR.              Director and Chairman of the Board
-------------------------------
   James M. Lapeyre, Jr.

/s/ DAVID C. BALDWIN                   Director
-------------------------------
   David C. Baldwin

/s/ ROBERT P. BRINDLEY                 Director
-------------------------------
   Robert P. Brindley

/s/ ERNEST E. COOK                     Director
-------------------------------
   Ernest E. Cook

/s/ THEODORE H. ELLIOTT, JR.           Director
-------------------------------
    Theodore H. Elliott, Jr.

/s/ ROBERT PEEBLER                     Director
-------------------------------
    Robert Peebles

                                       Director
-------------------------------
    Axel M. Sigmar

                                       Director
-------------------------------
    Sam K. Smith

/s/ WILLIAM F. WALLACE                 Director
-------------------------------
    William F. Wallace
</TABLE>
                                     -6-
<PAGE>


                                INDEX TO EXHIBITS


EXHIBIT    DESCRIPTION

   4.1     Amended and Restated Certificate of Incorporation, filed as
           Exhibit 3.1 to the Company's Annual Report on Form 10-K for the
           fiscal year ended May 31, 1995 and incorporated herein by
           reference.

   4.2     Certificate of Amendment to the Amended and Restated Certificate
           of Incorporation, dated October 11, 1996, filed as Exhibit 3.2 to
           the Company's Annual Report on Form 10-K for the fiscal year
           ended May 31, 1997 and incorporated herein by reference.

   4.3     Amended and Restated Bylaws, filed as Exhibit 3.2 to the Company's
           Annual Report on Form 10-K for the fiscal year ended May 31, 1995,
           is incorporated herein by reference.

   4.4     Specimen certificate for shares of the Company's common stock, par
           value $0.01 per share, filed as Exhibit F to the Company's
           Registration Statement on Form 8-A dated October 17, 1994, is
           incorporated herein by reference.

   4.5     Rights Agreement, dated as of January 17, 1997, by and between the
           Company and Harris Trust and Savings Bank, as Rights Agent,
           including exhibits thereto, filed as Exhibit 1 to the Company's
           Registration Statement on Form 8-A dated January 27, 1997, is
           incorporated herein by reference.

   4.6     Form of rights certificate to purchase Series A Preferred Stock,
           par value $0.01 per share, filed as Exhibit 3 to the Company's
           Registration Statement on Form 8-A dated January 27, 1997, is
           incorporated herein by reference.

   4.7     The Company's 2000 Restricted Stock Plan.

   5.1     Opinion of Haynes and Boone, L.L.P.

  23.1     Consent of KPMG LLP.

  23.2     Consent of Haynes and Boone, L.L.P. (included in Exhibit 5.1
           opinion).

  24.1     Power of Attorney (included on the signature page hereto).


                                     -7-
[{"type": "S-8", "sequence": "1", "description": "S-8", "secsgml_size_bytes": 22207}]
{"company-data": {"conformed-name": "INPUT OUTPUT INC", "cik": "0000866609", "assigned-sic": "3829", "irs-number": "222286646", "state-of-incorporation": "DE", "fiscal-year-end": "0531"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-36264", "film-number": "619300"}, "business-address": {"street1": "11104 W AIRPORT BLVD", "street2": "SUITE 200", "city": "STAFFORD", "state": "TX", "zip": "77477", "phone": "2819333339"}, "mail-address": {"street1": "11104 W AIRPORT BLVD", "street2": "SUITE 200", "city": "STAFFORD", "state": "TX", "zip": "77477"}}
As filed with the Securities and Exchange Commission on May 4, 2000
                                                     Registration  No. 333-_____

================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                -----------------

                                    FORM S-8
             REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

                                -----------------

                               INPUT/OUTPUT, INC.
             (Exact name of registrant as specified in its charter)

               DELAWARE                                     22-2286646
     (State or other jurisdiction                        (I.R.S. Employer
   of incorporation or organization)                  Identification Number)

                          11104 WEST AIRPORT BOULEVARD
                              STAFFORD, TEXAS 77477
                                 (281) 933-3339
       (Address, including zip code, and telephone number, including area
                code, of registrant's principal executive offices)

                                -----------------

                  INPUT/OUTPUT, INC. 2000 RESTRICTED STOCK PLAN
                              (Full Title of Plan)

                              C. ROBERT BUNCH, ESQ.
                               INPUT/OUTPUT, INC.
                          11104 WEST AIRPORT BOULEVARD
                              STAFFORD, TEXAS 77477
                                 (281) 933-3339
       (Name, address, including zip code, and telephone number, including
                        area code, of agent for service)

                                 WITH COPIES TO:
                            HAYNES AND BOONE, L.L.P.
                           1000 LOUISIANA, SUITE 4300
                              HOUSTON, TEXAS 77002
                             ATTN: MARC H. FOLLADORI
                                 (713) 547-2000

                                -----------------

                         CALCULATION OF REGISTRATION FEE
=========================================================================================================================
                                                                      PROPOSED
                                                                      MAXIMUM         PROPOSED MAXIMUM       AMOUNT OF
                 TITLE OF                       AMOUNT TO BE       OFFERING PRICE    AGGREGATE OFFERING    REGISTRATION
        SECURITIES TO BE REGISTERED           REGISTERED(1)(2)      PER SHARE(2)          PRICE(2)              FEE
-------------------------------------------------------------------------------------------------------------------------
Common Stock, par value $0.01 per share            200,000             $8.0625          $1,612,500.00         $425.70
=========================================================================================================================
(1)  Pursuant to Rule 416(c), also registered hereunder is an indeterminate
     number of shares of Common Stock issuable as a result of the anti-dilution
     provisions of the Input/Output, Inc. 2000 Restricted Stock Plan (the
     "Plan").

(2)  The 200,000 shares registered hereby represent shares issuable pursuant to
     the Plan. With respect to the shares registered hereby, the offering price
     per share, the aggregate offering price and the registration fee have been
     calculated in accordance with paragraphs (c) and (h)(1) of Rule 457 on the
     basis of the average high and low sale prices for the Company's Common
     Stock on May 2, 2000 as reported on the New York Stock Exchange composite
     tape ($8.0625 per share).
PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE.

         The contents of the following documents filed by Input/Output, Inc., a
Delaware corporation (the "Company"), with the Securities and Exchange
Commission (the "Commission") are incorporated into this registration statement
(this "Registration Statement") by reference:

         (a) The Company's Annual Report, dated August 20, 1999, as filed with
the Commission on Form 10-K, File No. 1-12691, for the fiscal year ended May 31,
1999;

         (b) All other reports filed pursuant to Section 13(a) or 15(d) of the
Securities Exchange Act of 1934, as amended (the "Exchange Act"), since May 31,
1999;

         (c) The description of the Company's common stock, par value $0.01 per
share (the "Common Stock"), contained in the Company's Registration Statement on
Form 8-A filed under Section 12(b) of the Exchange Act, dated October 17, 1994;
and

         (d) The description of the Company's rights to purchase Series A
Preferred Stock, par value $0.01 per share, contained in the Company's
Registration Statement on Form 8-A filed under Section 12(b) of the Exchange
Act, dated January 27, 1997.

         All documents filed by the Company with the Commission pursuant to
Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act subsequent to the filing
date of this Registration Statement and prior to the filing of a post-effective
amendment to this Registration Statement which indicates that all securities
offered have been sold or which deregisters all securities then remaining unsold
shall be deemed to be incorporated by reference in this Registration Statement
and to be a part hereof from the date of filing such documents.

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 permits a
corporation to indemnify any person who was or is a party or is threatened to be
made a party to any threatened, pending or completed action, suit or proceeding,
whether civil, criminal, administrative or investigative, by reason of the fact
that he is or was a director, officer, employee or agent of the corporation or
is or was serving at the request of the corporation as a director, officer,
employee or agent of another corporation, partnership, joint venture, trust or
other enterprise, against expenses (including attorney's fees), judgments, fines
and amounts paid in settlement actually and reasonably incurred by the person in
connection with such action, suit or proceeding.

         In an action brought to obtain a judgment in the corporation's favor,
whether by the corporation itself or derivatively by a stockholder, the
corporation may only indemnify for expenses, including attorney's fees, actually
and reasonably incurred in connection with the defense or settlement of such
action, and the corporation may not indemnify for amounts paid in satisfaction
of a judgment or in settlement of the claim. In any such action, no
indemnification may be paid in respect of any claim, issue or matter as to
which such person shall have been adjudged liable to the corporation except
as otherwise approved by the Delaware Court of Chancery or the court in which
the claim was brought. In any other

                                     -2-
type of proceeding, the indemnification may extend to judgments, fines and
amounts paid in settlement, actually and reasonably incurred in connection with
such other proceeding, as well as to expenses.

         The statute does not permit indemnification unless the person seeking
indemnification has acted in good faith and in a manner reasonably believed to
be in, or not opposed to, the best interests of the corporation and, in the case
of criminal actions or proceedings, the person had no reasonable cause to
believe his conduct was unlawful. The statute contains additional limitations
applicable to criminal actions and to actions brought by or in the name of the
corporation. The determination as to whether a person seeking indemnification
has met the required standard of conduct is to be made by the corporation only
as authorized in the specific case upon a determination that indemnification of
such person is proper in the circumstances. The determination as to whether a
person who is a director or officer at the time of such determination has met
the required standard of conduct is to be made (1) by a majority vote of the
disinterested directors, even though less than a quorum, (2) by a committee of
such directors designated by a majority vote of such directors, even though less
than a quorum, (3) if there are no disinterested directors or if the
disinterested directors so direct, by independent legal counsel in a written
opinion, or (4) by the stockholders.

         The Company's Bylaws require the Company to indemnify its directors,
officers, employees, and agents to the fullest extent permitted under Delaware
law. The Company's Certificate of Incorporation provides that a director of the
corporation shall not be held personally liable to the corporation or its
shareholders for monetary damages for breach of a director's fiduciary duty of
care, except that a director shall continue to be held personally liable for (i)
breach of the duty of loyalty, (ii) failure to act in good faith, (iii) engaging
in intentional misconduct or knowingly violating a law, (iv) paying a dividend
or approving a stock repurchase which was illegal under Delaware law, or (v)
obtaining an improper personal benefit.

         The Company has purchased insurance on behalf of its directors and
officers against certain liabilities that may be asserted against, or incurred
by, such persons in their capacities as directors or officers of the registrant,
or that may arise out of their status as directors or officers of the
registrant, including liabilities under the federal and state securities laws.

ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED.

         Not applicable.

ITEM 8. EXHIBITS.

Exhibit                           Description
-------                           -----------

  4.1     Amended and Restated Certificate of Incorporation, filed as
          Exhibit 3.1 to the Company's Annual Report on Form 10-K for the
          fiscal year ended May 31, 1995, is incorporated herein by reference.

  4.2     Certificate of Amendment to the Amended and Restated Certificate of
          Incorporation, dated October 11, 1996, filed as Exhibit 3.2 to the
          Company's Annual Report on Form 10-K for the fiscal year ended May 31,
          1997, is incorporated herein by reference.

  4.3     Amended and Restated Bylaws, filed as Exhibit 3.2 to the Company's
          Annual Report on Form 10-K for the fiscal year ended May 31, 1995,
          is incorporated herein by reference.

  4.4     Specimen certificate for shares of the Company's common stock, par
          value $0.01 per share, filed as Exhibit F to the Company's
          Registration Statement on Form 8-A dated October 17, 1994, is
          incorporated herein by reference.

                                     -3-
Exhibit                           Description
-------                           -----------

   4.5    Rights Agreement, dated as of January 17, 1997, by and between the
          Company and Harris Trust and Savings Bank, as Rights Agent, including
          exhibits thereto, filed as Exhibit 1 to the Company's Registration
          Statement on Form 8-A dated January 27, 1997, is incorporated herein
          by reference.

   4.6    Form of rights certificate to purchase Series A Preferred Stock, par
          value $0.01 per share, filed as Exhibit 3 to the Company's
          Registration Statement on Form 8-A dated January 27, 1997, is
          incorporated herein by reference.

   4.7    The Company's 2000 Restricted Stock Plan.

   5.1    Opinion of Haynes and Boone, L.L.P.

  23.1    Consent of KPMG LLP.

  23.2    Consent of Haynes and Boone, L.L.P. (included in Exhibit
          5.1 opinion).

  24.1    Power of Attorney (included on the signature page hereto).

ITEM 9.   UNDERTAKINGS.

          A.   UNDERTAKING TO UPDATE

               The undersigned 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 of 1933;

                   (ii)  To reflect in the prospectus any facts or events
               arising after the effective date of this 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 this Registration Statement; and

                   (iii) To include any material information with respect to
               the plan of distribution not previously disclosed in this
               Registration Statement or any material change to such information
               in this Registration Statement;

          PROVIDED, HOWEVER, that paragraphs (a)(1)(i) and (a)(1)(ii) do not
          apply if the information required to be included in a post-effective
          amendment by those paragraphs is contained in periodic reports
          filed with or furnished to the Commission by the registrant
          pursuant to Section 13 or Section 15(d) of the Exchange Act that
          are incorporated by reference in this Registration Statement.

               (2) That, for the purpose of determining any liability under
          the Securities Act of 1933, 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.

                                     -4-
(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.   UNDERTAKING WITH RESPECT TO DOCUMENTS INCORPORATED BY REFERENCE

               The undersigned registrant hereby undertakes that, for
               purposes of determining any liability under the Securities Act
               of 1933, each filing of the registrant's annual report pursuant
               to Section 13(a) or 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.   UNDERTAKING WITH RESPECT TO INDEMNIFICATION

               Insofar as indemnification for liabilities arising under the
               Securities Act of 1933 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
               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 Act and will be governed by the final adjudication of such
               issue.

                                     -5-
SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, the
Registrant certifies that it has reasonable grounds to believe that it meets all
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 Stafford, State of Texas, on April 27, 2000.

                                     INPUT/OUTPUT, INC.

                                     By: /s/ C. ROBERT BUNCH
                                        ---------------------------------------
                                           C. Robert Bunch
                                           Vice President, Chief Administrative
                                           Officer and Secretary
                                           (Principal Financial Officer)

                                POWER OF ATTORNEY

         Each of the undersigned hereby appoints Tim Probert and C. Robert
Bunch, and each of them (with full power to act alone), as attorney and agents
for the undersigned, with full power of substitution, for and in the name, place
and stead of the undersigned, to sign and file with the Securities and Exchange
Commission under the Securities Act of 1933 any and all amendments and exhibits
to this Registration Statement and any and all applications, instruments and
other documents to be filed with the Securities and Exchange Commission
pertaining to the registration of the securities covered hereby, with full power
and authority to do and perform any and all acts and things whatsoever requisite
or desirable.

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities indicated on April 27, 2000.
SIGNATURE                                       TITLE
         ---------                                       -----
/s/ TIM PROBERT                        Director, President and Chief Executive
-------------------------------        Officer (Principal Executive Officer)
    Tim Probert

/s/ C. ROBERT BUNCH                    Vice President, Chief Administrative
-------------------------------        Officer and Secretary
    C. Robert Bunch                    (Principal Financial Officer)

/s/ JAMES M. LAPEYRE, JR.              Director and Chairman of the Board
-------------------------------
   James M. Lapeyre, Jr.

/s/ DAVID C. BALDWIN                   Director
-------------------------------
   David C. Baldwin

/s/ ROBERT P. BRINDLEY                 Director
-------------------------------
   Robert P. Brindley

/s/ ERNEST E. COOK                     Director
-------------------------------
   Ernest E. Cook

/s/ THEODORE H. ELLIOTT, JR.           Director
-------------------------------
    Theodore H. Elliott, Jr.

/s/ ROBERT PEEBLER                     Director
-------------------------------
    Robert Peebles

                                       Director
-------------------------------
    Axel M. Sigmar

                                       Director
-------------------------------
    Sam K. Smith

/s/ WILLIAM F. WALLACE                 Director
-------------------------------
    William F. Wallace
-6-
INDEX TO EXHIBITS

EXHIBIT    DESCRIPTION

   4.1     Amended and Restated Certificate of Incorporation, filed as
           Exhibit 3.1 to the Company's Annual Report on Form 10-K for the
           fiscal year ended May 31, 1995 and incorporated herein by
           reference.

   4.2     Certificate of Amendment to the Amended and Restated Certificate
           of Incorporation, dated October 11, 1996, filed as Exhibit 3.2 to
           the Company's Annual Report on Form 10-K for the fiscal year
           ended May 31, 1997 and incorporated herein by reference.

   4.3     Amended and Restated Bylaws, filed as Exhibit 3.2 to the Company's
           Annual Report on Form 10-K for the fiscal year ended May 31, 1995,
           is incorporated herein by reference.

   4.4     Specimen certificate for shares of the Company's common stock, par
           value $0.01 per share, filed as Exhibit F to the Company's
           Registration Statement on Form 8-A dated October 17, 1994, is
           incorporated herein by reference.

   4.5     Rights Agreement, dated as of January 17, 1997, by and between the
           Company and Harris Trust and Savings Bank, as Rights Agent,
           including exhibits thereto, filed as Exhibit 1 to the Company's
           Registration Statement on Form 8-A dated January 27, 1997, is
           incorporated herein by reference.

   4.6     Form of rights certificate to purchase Series A Preferred Stock,
           par value $0.01 per share, filed as Exhibit 3 to the Company's
           Registration Statement on Form 8-A dated January 27, 1997, is
           incorporated herein by reference.

   4.7     The Company's 2000 Restricted Stock Plan.

   5.1     Opinion of Haynes and Boone, L.L.P.

  23.1     Consent of KPMG LLP.

  23.2     Consent of Haynes and Boone, L.L.P. (included in Exhibit 5.1
           opinion).

  24.1     Power of Attorney (included on the signature page hereto).

                                     -7-