As filed with the Securities and Exchange Commission on March 22, 2000.
                              Registration No. 333-
          -------------------------------------------------------------

                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549
                                 ---------------

                                    FORM S-8
                             Registration Statement
                                      Under
                           The Securities Act of 1933
                                 ---------------

                           THERMO ELECTRON CORPORATION
             (Exact name of registrant as specified in its charter)
                                 ---------------

      DELAWARE                                                        04-2209186
(State or other jurisdiction of                                (I.R.S. Employer
 incorporation or organization)                           Identification Number)

                                 81 Wyman Street
                        Waltham, Massachusetts 02454-9046
               (Address of Principal Executive Offices) (Zip Code)

 THERMO ELECTRON CORPORATION - ONIX SYSTEMS INC. NONQUALIFIED STOCK OPTION PLAN

             THERMO ELECTRON CORPORATION DIRECTORS STOCK OPTION PLAN
                                  (ONIX SHARES)

               THERMO INSTRUMENT SYSTEMS INC. - ONIX SYSTEMS INC.
                         NONQUALIFIED STOCK OPTION PLAN

           THERMO INSTRUMENT SYSTEMS INC. DIRECTORS STOCK OPTION PLAN
                                  (ONIX SHARES)

                     ONIX SYSTEMS INC. EQUITY INCENTIVE PLAN


                           (Full Titles of the Plans)
<PAGE>

                          Sandra L. Lambert, Secretary
                           Thermo Electron Corporation
                                 81 Wyman Street
                                 P. O. Box 9046
                        Waltham, Massachusetts 02454-9046
                     (Name and Address of Agent for Service)

                                 (781) 622-1000
          (Telephone Number, Including Area Code, of Agent For Service)

                                   Copies to:
                    Seth H. Hoogasian, Esq., General Counsel
                           Thermo Electron Corporation
                                 81 Wyman Street
                                 P. O. Box 9046
                        Waltham, Massachusetts 02454-9046

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

                         CALCULATION OF REGISTRATION FEE

 Title of                                       Proposed
 securities         Amount       Proposed       Maximum            Amount of
   to be            to be        Maximum        Aggregate         Registration
registered        registered     Offering       Offering             Fee
                                 Price Per       Price
                                   Share
  Common Stock,
 $1.00 par value     346,106      $21.40625   $7,408,831.562 (2)      $1,956
    per share         shares         (2)
                       (1)

     In addition, pursuant to Rule 416(c) under the Securities Act of 1933, this
Registration  Statement also covers an indeterminate  number of shares of Thermo
Electron's  common stock as may be issuable in connection with adjustments under
the employee benefit plans described herein to reflect certain changes in Thermo
Electron's capital structure, including stock dividends or stock splits.

(1)  The shares  registered  hereunder  are divided  among the various plans set
     forth below:

Thermo Electron Corporation - ONIX Systems Inc.  Nonqualified Stock Option Plan:
33,235 shares

Thermo Electron  Corporation  Directors  Stock Option Plan (ONIX Shares):  3,869
shares

Thermo  Instrument  Systems Inc. - ONIX Systems Inc.  Nonqualified  Stock Option
Plan: 20,525 shares

Thermo Instrument Systems Inc. Directors Stock Option Plan (ONIX Shares):  1,290
shares

ONIX Systems Inc. Equity Incentive Plan: 287,187 shares

(2)   Estimated  solely  for  the  purpose  of  calculating  the  amount  of the
      registration  fee in accordance  with Rule 457(h) under the Securities Act
      of 1933. The calculation of the proposed maximum aggregate  offering price
      has been based upon (1) the  registration  hereunder  of an  aggregate  of
      346,106  shares  and (2) the  average  of the high and low  sales  prices,
      $22.75 and $20.0625,  respectively,  of Thermo  Electron's common stock on
      the  New  York  Stock  Exchange  on  March  21,  2000 as  reported  in the
      consolidated transaction reporting system.

<PAGE>


                                     PART I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

      The information  required by Part I is included in documents sent or given
to the respective  participants in the plans  registered  hereunder  pursuant to
Rule 428(b)(1) under the Securities Act of 1933, as amended.


                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Documents by Reference.

      Thermo Electron is subject to the informational and reporting requirements
of Sections 13(a),  13(c), 14 and 15(d) of the Securities  Exchange Act of 1934,
as amended,  and in accordance  therewith  files reports,  proxy  statements and
other  information  with the Securities and Exchange  Commission.  The following
documents,  which  are on file with the  Commission,  are  incorporated  in this
Registration Statement by reference:

      (a)   Thermo  Electron's  Annual  Report on Form 10-K for the fiscal  year
            ended January 1, 2000.

      (b)   Thermo  Electron's  Current  Report  on  Form  8-K  filed  with  the
            Commission on February 1, 2000.

      (c)   The  description  of the common  stock which is  contained in Thermo
            Electron's  Registration  Statement  on Form  8-A  filed  under  the
            Exchange Act, as such description may be amended from time to time.

      (d)   The description of Thermo Electron's Preferred Stock Purchase Rights
            which is contained in Thermo  Electron's  Registration  Statement on
            Form 8-A filed under the Exchange  Act, as such  description  may be
            amended from time to time.

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

Item 4.  Description of Securities.

      Not applicable.
<PAGE>

Item 5.  Interests of Named Experts and Counsel.

     The  validity of the common  stock  offered  hereby has been passed upon by
Seth H. Hoogasian,  Esq., General Counsel of Thermo Electron. Mr. Hoogasian is a
full-time  employee of Thermo Electron,  is an officer of Thermo  Electron,  and
owns or has the right to  acquire  383,943  shares of common  stock and  162,177
shares of the common stock of Thermo Electron's subsidiaries.

Item 6.  Indemnification of Directors and Officers.

      The Delaware General Corporation Law and Thermo Electron's  Certificate of
Incorporation  and By-Laws  limit the monetary  liability of directors to Thermo
Electron  and to its  stockholders  and  provide for  indemnification  of Thermo
Electron's  officers and  directors for  liabilities  and expenses that they may
incur in such  capacities.  In general,  officers and directors are  indemnified
with respect to actions taken in good faith in a manner  reasonably  believed to
be in, or not  opposed  to, the best  interests  of Thermo  Electron  and,  with
respect to any criminal action or proceeding, actions that the indemnitee had no
reasonable   cause  to  believe  were   unlawful.   Thermo   Electron  also  has
indemnification  agreements with its directors and officers that provide for the
maximum indemnification allowed by law.

      Thermo  Electron has an insurance  policy which  insures the directors and
officers of Thermo Electron and its  subsidiaries  against  certain  liabilities
which might be incurred in connection with the performance of their duties.

Item 7.  Exemption from Registration Claimed.

      Not Applicable.

Item 8.  Exhibits.

      The Exhibit Index  immediately  preceding the exhibits is attached  hereto
and incorporated herein by reference.

Item 9.  Undertakings.

      (a)   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 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 20 percent  change in the maximum  aggregate
      offering price set forth in the "Calculation of Registration Fee" table in
      the effective registration statement;
<PAGE>

                  (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) 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 Thermo  Electron  pursuant to Section 13 or Section  15(d) of the
Securities  Exchange  Act of 1934  that are  incorporated  by  reference  in the
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.

            (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 undersigned  Registrant  hereby  undertakes  that, for purposes of
determining  any  liability  under the  Securities  Act of 1933,  each filing of
Thermo  Electron's  annual  report  pursuant  to  Section  13(a) or 15(d) of the
Securities  Exchange  Act of 1934  (and,  where  applicable,  each  filing of an
employee  benefit  plan's  annual  report  pursuant  to  Section  15(d)  of  the
Securities  Exchange  Act of 1934)  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 of 1933 may be permitted to directors,  officers and  controlling
persons of Thermo Electron pursuant to the foregoing  provisions,  or otherwise,
Thermo  Electron  has been  advised  that in the opinion of the  Securities  and
Exchange  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 Thermo
Electron of expenses  incurred  or paid by a  director,  officer or  controlling
person of Thermo  Electron  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, Thermo Electron 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.


<PAGE>


                                   SIGNATURES

      Pursuant  to the  requirements  of the  Securities  Act  of  1933,  Thermo
Electron  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 Waltham, Commonwealth of Massachusetts,  on this 22nd
day of March, 2000.

                                    THERMO ELECTRON CORPORATION


                                    By:  /s/ Richard F. Syron
                                         ---------------------------------------
                                         Richard F. Syron
                                    Its: President, Chief Executive Officer and
                                         Chairman of the Board of Directors


                                POWER OF ATTORNEY

     Each  of  the  undersigned   Directors  and  Officers  of  Thermo  Electron
Corporation  hereby appoints Theo  Melas-Kyriazi,  Kenneth J. Apicerno,  Seth H.
Hoogasian  and  Sandra  L.  Lambert,  and  each of them,  his  true  and  lawful
attorneys-in-fact  and agents,  with full power of substitution,  for him and in
his  name,  place  and  stead,  in any and all  capacities,  to sign any and all
amendments (including post-effective amendments) to this Registration Statement,
and to file the same, with all exhibits thereto, and all documents in connection
therewith,  with the  Securities  and Exchange  Commission,  granting  unto said
attorneys-in-fact  and agents,  and each of them, full power and authority to do
and perform each and every act and thing  requisite  and necessary to be done in
and about the  premises,  as fully to all  intents  and  purposes as he might or
could  do  in  person,   hereby   ratifying   and   confirming   all  that  said
attorneys-in-fact  and  agents  or any of them,  or their or his  substitute  or
substitutes, may lawfully do or cause to be done by virtue thereof.

      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

                              President, Chief Executive
/s/ Richard F. Syron          Officer and Chairman of
_________________________     the Board                     March 22, 2000
Richard F. Syron
<PAGE>

/s/ Theo Melas-Kyriazi        Chief Financial Officer
_________________________                                   March 22, 2000
Theo Melas-Kyriazi

/s/ Paul F.Kelleher           Chief Accounting Officer
_________________________                                   March 22, 2000
Paul F. Kelleher

/s/ George N. Hatsopoulos
_________________________     Chairman Emeritus             March 22, 2000
George N. Hatsopoulos

/s/ Samuel W.Bodman           Director                      March 22, 2000
_________________________
Samuel W. Bodman

/s/ Peter O. Crisp            Director                      March 22, 2000
_________________________
Peter O. Crisp

/s/ Elias P. Gyftopoulos      Director                      March 22, 2000
_________________________
Elias P. Gyftopoulos

/s/ Frank Jungers             Director                      March 22, 2000
_________________________
Frank Jungers

/s/ Robert A. McCabe          Director                      March 22, 2000
_________________________
Robert A. McCabe

/s/ Hutham S. Olayan          Director                      March 22, 2000
_________________________
Hutham S. Olayan

/s/ Robert W. O'Leary         Director                      March 22, 2000
_________________________
Robert W. O'Leary

/s/ Roger D. Wellington       Director                      March 22, 2000
_________________________
Roger D. Wellington



<PAGE>


                                  EXHIBIT INDEX


Exhibit
Number            Description


5         Opinion of Seth H. Hoogasian, Esq.

23.1      Consent of Arthur Andersen LLP

23.2      Consent of Seth H. Hoogasian, Esq. (contained in his opinion filed
          as Exhibit 5).

24        Power of Attorney (see signature pages to this Registration
          Statement).



<PAGE>





                                                                       EXHIBIT 5



                           Thermo Electron Corporation
                                 81 Wyman Street
                        Waltham, Massachusetts 02454-9046




                                        March 22, 2000

Thermo Electron Corporation
81 Wyman Street
Waltham, Massachusetts 02454-9046

Re:   Registration Statement on Form S-8 Relating to 346,106 Shares of the
      Common Stock, $1.00 par value, of Thermo Electron Corporation

Dear Sirs:

      I  am  General  Counsel  to  Thermo  Electron   Corporation,   a  Delaware
corporation  (the  "Company"),  and have acted as counsel in connection with the
registration  under the  Securities  Act of 1933,  as amended,  on Form S-8 (the
"Registration Statement"),  of 346,106 shares of Thermo Electron's Common Stock,
$1.00  par value  per  share  (the  "Shares")  subject  to the  Thermo  Electron
Corporation  - ONIX Systems  Inc.  Nonqualified  Stock  Option Plan,  the Thermo
Electron  Corporation  Directors  Stock  Option Plan (ONIX  Shares),  the Thermo
Instrument Systems Inc. - ONIX Systems Inc.  Nonqualified Stock Option Plan, the
Thermo Instrument  Systems Inc.  Directors Stock Option Plan (ONIX Shares),  and
the ONIX Systems Inc. Equity Incentive Plan (collectively, the "Plans").

      I or a member of my legal staff have  reviewed the  corporate  proceedings
taken by Thermo  Electron with respect to the  authorization  of the issuance of
the Shares.  I or a member of my legal staff have also  examined and relied upon
originals or copies, certified or otherwise authenticated to my satisfaction, of
all corporate  records,  documents,  agreements or other  instruments  of Thermo
Electron and have made all  investigations of law and have discussed with Thermo
Electron's representatives all questions of fact that I have deemed necessary or
appropriate.

      Based upon and subject to the foregoing, I am of the opinion that:

      1. Thermo Electron is a corporation validly existing and in corporate good
standing under the laws of the State of Delaware.

      2. The issuance and sale of the Shares as contemplated in the Registration
Statement have been duly authorized by Thermo Electron.

      3. The Shares,  when issued and sold in accordance  with the provisions of
the respective Plans, will be validly issued, fully paid and nonassessable.


      I hereby  consent  to the  filing  of this  opinion  as  Exhibit  5 to the
Registration Statement.

                                        Very truly yours,


                                        /s/ Seth H. Hoogasian
                                        _________________________
                                        Seth H. Hoogasian
                                        General Counsel


<PAGE>


                                                                    Exhibit 23.1




                    Consent of Independent Public Accountants


     As independent public  accountants,  we hereby consent to the incorporation
by reference  in this  registration  statement on Form S-8 of our reports  dated
February 17, 2000 (except for the matters  discussed in Note 17, as to which the
date is March 7, 2000), included in Thermo Electron  Corporation's Annual Report
on Form 10-K for the year ended  January 1, 2000,  and to all  references to our
Firm included in this registration statement.


Arthur Andersen LLP



Boston, Massachusetts
March 21, 2000
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 21215}]
{"company-data": {"conformed-name": "THERMO ELECTRON CORP", "cik": "0000097745", "assigned-sic": "3829", "irs-number": "042209186", "state-of-incorporation": "DE", "fiscal-year-end": "0102"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-33066", "film-number": "576009"}, "business-address": {"street1": "81 WYMAN ST", "street2": "P O BOX 9046", "city": "WALTHAM", "state": "MA", "zip": "02454", "phone": "7816221000"}}
As filed with the Securities and Exchange Commission on March 22, 2000.
                              Registration No. 333-
          -------------------------------------------------------------

                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549
                                 ---------------

                                    FORM S-8
                             Registration Statement
                                      Under
                           The Securities Act of 1933
                                 ---------------

                           THERMO ELECTRON CORPORATION
             (Exact name of registrant as specified in its charter)
                                 ---------------

      DELAWARE                                                        04-2209186
(State or other jurisdiction of                                (I.R.S. Employer
 incorporation or organization)                           Identification Number)

                                 81 Wyman Street
                        Waltham, Massachusetts 02454-9046
               (Address of Principal Executive Offices) (Zip Code)

 THERMO ELECTRON CORPORATION - ONIX SYSTEMS INC. NONQUALIFIED STOCK OPTION PLAN

             THERMO ELECTRON CORPORATION DIRECTORS STOCK OPTION PLAN
                                  (ONIX SHARES)

               THERMO INSTRUMENT SYSTEMS INC. - ONIX SYSTEMS INC.
                         NONQUALIFIED STOCK OPTION PLAN

           THERMO INSTRUMENT SYSTEMS INC. DIRECTORS STOCK OPTION PLAN
                                  (ONIX SHARES)

                     ONIX SYSTEMS INC. EQUITY INCENTIVE PLAN

                           (Full Titles of the Plans)
Sandra L. Lambert, Secretary
                           Thermo Electron Corporation
                                 81 Wyman Street
                                 P. O. Box 9046
                        Waltham, Massachusetts 02454-9046
                     (Name and Address of Agent for Service)

                                 (781) 622-1000
          (Telephone Number, Including Area Code, of Agent For Service)

                                   Copies to:
                    Seth H. Hoogasian, Esq., General Counsel
                           Thermo Electron Corporation
                                 81 Wyman Street
                                 P. O. Box 9046
                        Waltham, Massachusetts 02454-9046

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

                         CALCULATION OF REGISTRATION FEE

 Title of                                       Proposed
 securities         Amount       Proposed       Maximum            Amount of
   to be            to be        Maximum        Aggregate         Registration
registered        registered     Offering       Offering             Fee
                                 Price Per       Price
                                   Share
  Common Stock,
 $1.00 par value     346,106      $21.40625   $7,408,831.562 (2)      $1,956
    per share         shares         (2)
                       (1)

     In addition, pursuant to Rule 416(c) under the Securities Act of 1933, this
Registration  Statement also covers an indeterminate  number of shares of Thermo
Electron's  common stock as may be issuable in connection with adjustments under
the employee benefit plans described herein to reflect certain changes in Thermo
Electron's capital structure, including stock dividends or stock splits.

(1)  The shares  registered  hereunder  are divided  among the various plans set
     forth below:

Thermo Electron Corporation - ONIX Systems Inc.  Nonqualified Stock Option Plan:
33,235 shares

Thermo Electron  Corporation  Directors  Stock Option Plan (ONIX Shares):  3,869
shares

Thermo  Instrument  Systems Inc. - ONIX Systems Inc.  Nonqualified  Stock Option
Plan: 20,525 shares

Thermo Instrument Systems Inc. Directors Stock Option Plan (ONIX Shares):  1,290
shares

ONIX Systems Inc. Equity Incentive Plan: 287,187 shares

(2)   Estimated  solely  for  the  purpose  of  calculating  the  amount  of the
      registration  fee in accordance  with Rule 457(h) under the Securities Act
      of 1933. The calculation of the proposed maximum aggregate  offering price
      has been based upon (1) the  registration  hereunder  of an  aggregate  of
      346,106  shares  and (2) the  average  of the high and low  sales  prices,
      $22.75 and $20.0625,  respectively,  of Thermo  Electron's common stock on
      the  New  York  Stock  Exchange  on  March  21,  2000 as  reported  in the
      consolidated transaction reporting system.
PART I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

      The information  required by Part I is included in documents sent or given
to the respective  participants in the plans  registered  hereunder  pursuant to
Rule 428(b)(1) under the Securities Act of 1933, as amended.

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Documents by Reference.

      Thermo Electron is subject to the informational and reporting requirements
of Sections 13(a),  13(c), 14 and 15(d) of the Securities  Exchange Act of 1934,
as amended,  and in accordance  therewith  files reports,  proxy  statements and
other  information  with the Securities and Exchange  Commission.  The following
documents,  which  are on file with the  Commission,  are  incorporated  in this
Registration Statement by reference:

      (a)   Thermo  Electron's  Annual  Report on Form 10-K for the fiscal  year
            ended January 1, 2000.

      (b)   Thermo  Electron's  Current  Report  on  Form  8-K  filed  with  the
            Commission on February 1, 2000.

      (c)   The  description  of the common  stock which is  contained in Thermo
            Electron's  Registration  Statement  on Form  8-A  filed  under  the
            Exchange Act, as such description may be amended from time to time.

      (d)   The description of Thermo Electron's Preferred Stock Purchase Rights
            which is contained in Thermo  Electron's  Registration  Statement on
            Form 8-A filed under the Exchange  Act, as such  description  may be
            amended from time to time.

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

Item 4.  Description of Securities.

      Not applicable.
Item 5.  Interests of Named Experts and Counsel.

     The  validity of the common  stock  offered  hereby has been passed upon by
Seth H. Hoogasian,  Esq., General Counsel of Thermo Electron. Mr. Hoogasian is a
full-time  employee of Thermo Electron,  is an officer of Thermo  Electron,  and
owns or has the right to  acquire  383,943  shares of common  stock and  162,177
shares of the common stock of Thermo Electron's subsidiaries.

Item 6.  Indemnification of Directors and Officers.

      The Delaware General Corporation Law and Thermo Electron's  Certificate of
Incorporation  and By-Laws  limit the monetary  liability of directors to Thermo
Electron  and to its  stockholders  and  provide for  indemnification  of Thermo
Electron's  officers and  directors for  liabilities  and expenses that they may
incur in such  capacities.  In general,  officers and directors are  indemnified
with respect to actions taken in good faith in a manner  reasonably  believed to
be in, or not  opposed  to, the best  interests  of Thermo  Electron  and,  with
respect to any criminal action or proceeding, actions that the indemnitee had no
reasonable   cause  to  believe  were   unlawful.   Thermo   Electron  also  has
indemnification  agreements with its directors and officers that provide for the
maximum indemnification allowed by law.

      Thermo  Electron has an insurance  policy which  insures the directors and
officers of Thermo Electron and its  subsidiaries  against  certain  liabilities
which might be incurred in connection with the performance of their duties.

Item 7.  Exemption from Registration Claimed.

      Not Applicable.

Item 8.  Exhibits.

      The Exhibit Index  immediately  preceding the exhibits is attached  hereto
and incorporated herein by reference.

Item 9.  Undertakings.

      (a)   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 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 20 percent  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) 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 Thermo  Electron  pursuant to Section 13 or Section  15(d) of the
Securities  Exchange  Act of 1934  that are  incorporated  by  reference  in the
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.

            (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 undersigned  Registrant  hereby  undertakes  that, for purposes of
determining  any  liability  under the  Securities  Act of 1933,  each filing of
Thermo  Electron's  annual  report  pursuant  to  Section  13(a) or 15(d) of the
Securities  Exchange  Act of 1934  (and,  where  applicable,  each  filing of an
employee  benefit  plan's  annual  report  pursuant  to  Section  15(d)  of  the
Securities  Exchange  Act of 1934)  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 of 1933 may be permitted to directors,  officers and  controlling
persons of Thermo Electron pursuant to the foregoing  provisions,  or otherwise,
Thermo  Electron  has been  advised  that in the opinion of the  Securities  and
Exchange  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 Thermo
Electron of expenses  incurred  or paid by a  director,  officer or  controlling
person of Thermo  Electron  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, Thermo Electron 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.
SIGNATURES

      Pursuant  to the  requirements  of the  Securities  Act  of  1933,  Thermo
Electron  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 Waltham, Commonwealth of Massachusetts,  on this 22nd
day of March, 2000.

                                    THERMO ELECTRON CORPORATION

                                    By:  /s/ Richard F. Syron
                                         ---------------------------------------
                                         Richard F. Syron
                                    Its: President, Chief Executive Officer and
                                         Chairman of the Board of Directors

                                POWER OF ATTORNEY

     Each  of  the  undersigned   Directors  and  Officers  of  Thermo  Electron
Corporation  hereby appoints Theo  Melas-Kyriazi,  Kenneth J. Apicerno,  Seth H.
Hoogasian  and  Sandra  L.  Lambert,  and  each of them,  his  true  and  lawful
attorneys-in-fact  and agents,  with full power of substitution,  for him and in
his  name,  place  and  stead,  in any and all  capacities,  to sign any and all
amendments (including post-effective amendments) to this Registration Statement,
and to file the same, with all exhibits thereto, and all documents in connection
therewith,  with the  Securities  and Exchange  Commission,  granting  unto said
attorneys-in-fact  and agents,  and each of them, full power and authority to do
and perform each and every act and thing  requisite  and necessary to be done in
and about the  premises,  as fully to all  intents  and  purposes as he might or
could  do  in  person,   hereby   ratifying   and   confirming   all  that  said
attorneys-in-fact  and  agents  or any of them,  or their or his  substitute  or
substitutes, may lawfully do or cause to be done by virtue thereof.

      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

                              President, Chief Executive
/s/ Richard F. Syron          Officer and Chairman of
_________________________     the Board                     March 22, 2000
Richard F. Syron
/s/ Theo Melas-Kyriazi        Chief Financial Officer
_________________________                                   March 22, 2000
Theo Melas-Kyriazi

/s/ Paul F.Kelleher           Chief Accounting Officer
_________________________                                   March 22, 2000
Paul F. Kelleher

/s/ George N. Hatsopoulos
_________________________     Chairman Emeritus             March 22, 2000
George N. Hatsopoulos

/s/ Samuel W.Bodman           Director                      March 22, 2000
_________________________
Samuel W. Bodman

/s/ Peter O. Crisp            Director                      March 22, 2000
_________________________
Peter O. Crisp

/s/ Elias P. Gyftopoulos      Director                      March 22, 2000
_________________________
Elias P. Gyftopoulos

/s/ Frank Jungers             Director                      March 22, 2000
_________________________
Frank Jungers

/s/ Robert A. McCabe          Director                      March 22, 2000
_________________________
Robert A. McCabe

/s/ Hutham S. Olayan          Director                      March 22, 2000
_________________________
Hutham S. Olayan

/s/ Robert W. O'Leary         Director                      March 22, 2000
_________________________
Robert W. O'Leary

/s/ Roger D. Wellington       Director                      March 22, 2000
_________________________
Roger D. Wellington
EXHIBIT INDEX

Exhibit
Number            Description

5         Opinion of Seth H. Hoogasian, Esq.

23.1      Consent of Arthur Andersen LLP

23.2      Consent of Seth H. Hoogasian, Esq. (contained in his opinion filed
          as Exhibit 5).

24        Power of Attorney (see signature pages to this Registration
          Statement).
EXHIBIT 5

                           Thermo Electron Corporation
                                 81 Wyman Street
                        Waltham, Massachusetts 02454-9046

                                        March 22, 2000

Thermo Electron Corporation
81 Wyman Street
Waltham, Massachusetts 02454-9046

Re:   Registration Statement on Form S-8 Relating to 346,106 Shares of the
      Common Stock, $1.00 par value, of Thermo Electron Corporation

Dear Sirs:

      I  am  General  Counsel  to  Thermo  Electron   Corporation,   a  Delaware
corporation  (the  "Company"),  and have acted as counsel in connection with the
registration  under the  Securities  Act of 1933,  as amended,  on Form S-8 (the
"Registration Statement"),  of 346,106 shares of Thermo Electron's Common Stock,
$1.00  par value  per  share  (the  "Shares")  subject  to the  Thermo  Electron
Corporation  - ONIX Systems  Inc.  Nonqualified  Stock  Option Plan,  the Thermo
Electron  Corporation  Directors  Stock  Option Plan (ONIX  Shares),  the Thermo
Instrument Systems Inc. - ONIX Systems Inc.  Nonqualified Stock Option Plan, the
Thermo Instrument  Systems Inc.  Directors Stock Option Plan (ONIX Shares),  and
the ONIX Systems Inc. Equity Incentive Plan (collectively, the "Plans").

      I or a member of my legal staff have  reviewed the  corporate  proceedings
taken by Thermo  Electron with respect to the  authorization  of the issuance of
the Shares.  I or a member of my legal staff have also  examined and relied upon
originals or copies, certified or otherwise authenticated to my satisfaction, of
all corporate  records,  documents,  agreements or other  instruments  of Thermo
Electron and have made all  investigations of law and have discussed with Thermo
Electron's representatives all questions of fact that I have deemed necessary or
appropriate.

      Based upon and subject to the foregoing, I am of the opinion that:

      1. Thermo Electron is a corporation validly existing and in corporate good
standing under the laws of the State of Delaware.

      2. The issuance and sale of the Shares as contemplated in the Registration
Statement have been duly authorized by Thermo Electron.

      3. The Shares,  when issued and sold in accordance  with the provisions of
the respective Plans, will be validly issued, fully paid and nonassessable.

      I hereby  consent  to the  filing  of this  opinion  as  Exhibit  5 to the
Registration Statement.

                                        Very truly yours,

                                        /s/ Seth H. Hoogasian
                                        _________________________
                                        Seth H. Hoogasian
                                        General Counsel
Exhibit 23.1

                    Consent of Independent Public Accountants

     As independent public  accountants,  we hereby consent to the incorporation
by reference  in this  registration  statement on Form S-8 of our reports  dated
February 17, 2000 (except for the matters  discussed in Note 17, as to which the
date is March 7, 2000), included in Thermo Electron  Corporation's Annual Report
on Form 10-K for the year ended  January 1, 2000,  and to all  references to our
Firm included in this registration statement.

Arthur Andersen LLP

Boston, Massachusetts
March 21, 2000