<PAGE>   1

      As filed with the Securities and Exchange Commission on May 15, 2001

                                                    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)

                           12300 C. E. SELECMAN DRIVE
                              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. NON-EMPLOYEE DIRECTORS' RETAINER PLAN
                              (Full Title of Plan)

                              C. ROBERT BUNCH, ESQ.
                               INPUT/OUTPUT, INC.
                           12300 C. E. SELECMAN DRIVE
                              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        REGISTRATION
       SECURITIES TO BE REGISTERED            REGISTERED(1)      PER SHARE(1)    OFFERING PRICE(1)        FEE
------------------------------------------------------------------------------------------------------------------
<S>                                            <C>               <C>             <C>                   <C>
Common Stock, par value $0.01 per share           100,000            $12.335         $1,235,500         $310.00
==================================================================================================================
</TABLE>

(1)  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
     9, 2001 as reported on the New York Stock Exchange composite tape ($12.335
     per share).


<PAGE>   2


                                     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 Transition Report on Form 10-K, dated March 19, 2001,
as filed with the Commission, File No. 1-13402, for the seven months ended
December 31, 2000;

         (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 December
31, 2000;

         (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, as amended by the Company's Amended Registration
Statement on Form 8-A/A-1 filed under Section 12(b) of the Exchange Act, dated
May 7, 1999.

         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.

<PAGE>   3


         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 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
stockholders 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 Transition Report on Form 10-K for the seven
         months ended December 31, 2000, 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 3.1 to the Company's
         Quarterly Report on Form 10-Q for the quarterly period ended August 31,
         2000, 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 Non-Employee Directors' Retainer Plan.

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

15.1     Acknowledgement Letter Regarding Unaudited Interim Financial
         Information from KPMG LLP.

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

<PAGE>   4

               amendment thereof) which, individually or in the aggregate,
               represent a fundamental change in the information set forth in
               this 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 a prospectus filed with the Securities and Exchange
               Commission pursuant to Rule 424(b) if, in the aggregate, the
               changes in volume and price represent no more than a 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 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.

               (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 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. 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,

<PAGE>   5


         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>   6


                                   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 this 30th day of April,
2001.


                                         INPUT/OUTPUT, INC.


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

                                POWER OF ATTORNEY

         Each of the undersigned hereby appoints Timothy J. 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 30, 2001.


               SIGNATURE                              TITLE
               ---------                              -----

/s/ Timothy J. Probert           Director, President and Chief Executive Officer
--------------------------       (Principal Executive Officer)
    Timothy J.  Probert


/s/ C. Robert Bunch               Vice President, Chief Administrative Officer
--------------------------        and Secretary (Principal Financial and
     C. Robert Bunch              Accounting 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/ Ernest E. Cook                Director
---------------------------
     Ernest E. Cook

/s/ Theodore H. Elliott, Jr.      Director
---------------------------
    Theodore H. Elliott, Jr.

/s/ Robert P. Peebler             Director
---------------------------
     Robert P. Peebler

/s/ Sam K. Smith                  Director
---------------------------
    Sam K. Smith

/s/ William F. Wallace            Director
---------------------------
     William F. Wallace


<PAGE>   7


                                INDEX TO EXHIBITS


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

  4.1          Amended and Restated Certificate of Incorporation, filed as
               Exhibit 3.1 to the Company's Transition Report on Form 10-K for
               the seven months ended December 31, 2000, 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 and incorporated herein by
               reference.

 4.3           Amended and Restated Bylaws, filed as Exhibit 3.1 to the
               Company's Quarterly Report on Form 10-Q for the quarterly period
               ended August 31, 2000, 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 Non-Employee Directors' Retainer Plan.

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

15.1           Acknowledgement Letter Regarding Unaudited Interim Financial
               Information from KPMG LLP.

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).
[{"type": "S-8", "sequence": "1", "filename": "h87199s-8.txt", "description": "INPUT/OUTPUT INC", "secsgml_size_bytes": 22401}]
{"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": "333-60950", "film-number": "1639504"}, "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"}}
1

      As filed with the Securities and Exchange Commission on May 15, 2001

                                                    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)

                           12300 C. E. SELECMAN DRIVE
                              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. NON-EMPLOYEE DIRECTORS' RETAINER PLAN
                              (Full Title of Plan)

                              C. ROBERT BUNCH, ESQ.
                               INPUT/OUTPUT, INC.
                           12300 C. E. SELECMAN DRIVE
                              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        REGISTRATION
       SECURITIES TO BE REGISTERED            REGISTERED(1)      PER SHARE(1)    OFFERING PRICE(1)        FEE
------------------------------------------------------------------------------------------------------------------
Common Stock, par value $0.01 per share           100,000            $12.335         $1,235,500         $310.00
==================================================================================================================
(1)  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
     9, 2001 as reported on the New York Stock Exchange composite tape ($12.335
     per share).
2

                                     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 Transition Report on Form 10-K, dated March 19, 2001,
as filed with the Commission, File No. 1-13402, for the seven months ended
December 31, 2000;

         (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 December
31, 2000;

         (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, as amended by the Company's Amended Registration
Statement on Form 8-A/A-1 filed under Section 12(b) of the Exchange Act, dated
May 7, 1999.

         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.
3

         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 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
stockholders 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 Transition Report on Form 10-K for the seven
         months ended December 31, 2000, 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 3.1 to the Company's
         Quarterly Report on Form 10-Q for the quarterly period ended August 31,
         2000, 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 Non-Employee Directors' Retainer Plan.

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

15.1     Acknowledgement Letter Regarding Unaudited Interim Financial
         Information from KPMG LLP.

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
4

               amendment thereof) which, individually or in the aggregate,
               represent a fundamental change in the information set forth in
               this 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 a prospectus filed with the Securities and Exchange
               Commission pursuant to Rule 424(b) if, in the aggregate, the
               changes in volume and price represent no more than a 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 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.

               (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 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. 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,
5

         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.
6

                                   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 this 30th day of April,
2001.

                                         INPUT/OUTPUT, INC.

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

                                POWER OF ATTORNEY

         Each of the undersigned hereby appoints Timothy J. 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 30, 2001.

               SIGNATURE                              TITLE
               ---------                              -----

/s/ Timothy J. Probert           Director, President and Chief Executive Officer
--------------------------       (Principal Executive Officer)
    Timothy J.  Probert

/s/ C. Robert Bunch               Vice President, Chief Administrative Officer
--------------------------        and Secretary (Principal Financial and
     C. Robert Bunch              Accounting 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/ Ernest E. Cook                Director
---------------------------
     Ernest E. Cook

/s/ Theodore H. Elliott, Jr.      Director
---------------------------
    Theodore H. Elliott, Jr.

/s/ Robert P. Peebler             Director
---------------------------
     Robert P. Peebler

/s/ Sam K. Smith                  Director
---------------------------
    Sam K. Smith

/s/ William F. Wallace            Director
---------------------------
     William F. Wallace
7

                                INDEX TO EXHIBITS

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

  4.1          Amended and Restated Certificate of Incorporation, filed as
               Exhibit 3.1 to the Company's Transition Report on Form 10-K for
               the seven months ended December 31, 2000, 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 and incorporated herein by
               reference.

 4.3           Amended and Restated Bylaws, filed as Exhibit 3.1 to the
               Company's Quarterly Report on Form 10-Q for the quarterly period
               ended August 31, 2000, 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 Non-Employee Directors' Retainer Plan.

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

15.1           Acknowledgement Letter Regarding Unaudited Interim Financial
               Information from KPMG LLP.

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).