<PAGE>
    AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON FEBRUARY 10, 2004

                              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 PARC CREST DR.
                              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. 2003 EMPLOYEE STOCK OPTION PLAN
                              (FULL TITLE OF PLAN)

                               J. MICHAEL KIRKSEY
                       EXECUTIVE VICE PRESIDENT AND CHIEF
                                FINANCIAL OFFICER
                               INPUT/OUTPUT, INC.
                              12300 PARC CREST DR.
                              STAFFORD, TEXAS 77477
                                 (281) 933-3339

       (NAME, ADDRESS, INCLUDING ZIP CODE, AND TELEPHONE NUMBER, INCLUDING
                        AREA CODE, OF AGENT FOR SERVICE)

                                 WITH COPIES TO:
                           FULBRIGHT& JAWORSKI L.L.P.
                            1301 MCKINNEY, SUITE 5100
                              HOUSTON, TEXAS 77010
                          ATTENTION: MARC H. FOLLADORI
                                 (713) 651-5151

                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
==========================================================================================================
                                                 PROPOSED            PROPOSED MAXIMUM
TITLE OF SECURITIES       AMOUNT TO           MAXIMUM OFFERING      AGGREGATE OFFERING        AMOUNT OF
TO BE REGISTERED      BE REGISTERED(1)(2)    PRICE PER SHARE(2)          PRICE(2)         REGISTRATION FEE
----------------------------------------------------------------------------------------------------------
<S>                   <C>                    <C>                    <C>                   <C>
 Common Stock
 $.01 par value        1,500,000 shares          $5.17                 $7,755,000.00           $982.56
==========================================================================================================
</TABLE>

(1)     Pursuant to Rule 416(a), 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. 2003 Employee Stock
        Option Plan (the "Plan").

(2)     The 1,500,000 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 February 5, 2004 as reported on
        the New York Stock Exchange composite tape.

================================================================================
<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:

         -        The Company's Annual Report on Form 10-K for the year ended
                  December 31, 2002;

         -        The Company's Quarterly Reports on Form 10-Q for the quarters
                  ended March 31, 2003, June 30, 2003 September 30, 2003, and on
                  Form 10-Q/A for the quarters ended June 30 and September 30,
                  2003;

         -        The Company's Current Reports on Form 8-K filed on March 31,
                  April 17, December 4, December 5 and December 17, 2003;

         -        The description of the Company's common stock contained in the
                  Company's registration statement on Form 8-A dated October 14,
                  1994 filed under Section 12(b) of the Exchange Act, as amended
                  by the Company's Current Report on Form 8-K filed on March 8,
                  2002; and

         -        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-A12B filed on
                  January 27, 1997, as amended by the Company's amended
                  registration statement on Form 8-A12B/A filed on 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 of such documents.

ITEM 4.  DESCRIPTION OF SECURITIES

         Not Applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.

         Not Applicable.

                                      II-2
<PAGE>

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         The General Corporation Law of the State of Delaware ("DGCL") permits
the Company and its stockholders to limit directors' exposure to liability for
certain breaches of the directors' fiduciary duty, either in a suit on behalf of
the Company or in an action by stockholders of the Company. The Certificate of
Incorporation of the Company (the "Charter") provides that a director of the
Company shall not be personally liable to the Company or its stockholders for
monetary damages for breach of fiduciary duty as a director, except for
liability (i) for any breach of the director's duty of loyalty to the Company or
its stockholders, (ii) for acts or omissions not in good faith or which involve
intentional misconduct or a knowing violation of law, (iii) under Section 174 of
the General Corporation Law of the State of Delaware, or (iv) for any
transaction from which the director derived an improper personal benefit.

         The Amended and Restated Bylaws (the "Bylaws") of the Company provide
that the Company shall, to the full extent permitted by applicable laws
(including the DGCL), indemnify its directors, officers, employees and agents
with respect to expenses (including counsel fees), judgments, fines, penalties,
other liabilities and amounts incurred by any such person in connection with any
threatened, pending or completed action, suit or proceeding to which such person
is or was a party, or is or was threatened to be made a party, by reason of the
fact that such person is or was serving as a director, officer, employee or
agent of the Company or any of its subsidiaries, or is or was serving at the
request of the Company or any of its subsidiaries as a director, officer,
employee, agent or trustee of another corporation, partnership, joint venture,
trust, employee benefit plan or other enterprise. The Bylaws provide that the
indemnification provided pursuant to the Bylaws is not exclusive of any other
rights to which those seeking indemnification may be entitled under any
provision of law, certificate of incorporation, bylaws, governing documents,
agreement, vote of stockholders or disinterested directors or otherwise. The
Company has entered into indemnification agreements with each of its officers
and directors and intends to enter into indemnification agreements with each of
its future officers and directors. Pursuant to such indemnification agreements,
the Company has agreed to indemnify its officers and directors against certain
liabilities.

         The Company maintains a standard form of officers' and directors'
liability insurance policy which provides coverage to the officers and directors
of the Company for certain liabilities, including certain liabilities which may
arise out of this Registration Statement.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

         Not applicable.

                                      II-3
<PAGE>

ITEM 8. EXHIBITS

                  4.1      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, which
                           is incorporated by reference herein, as amended by
                           the First Amendment to Rights Agreement, dated as of
                           April 21, 1999, by and between the Company and Harris
                           Trust and Savings Bank, as Rights Agent, filed as
                           Exhibit 10.3 to the Company's Current Report on Form
                           8-K filed on May 7, 1999, which is incorporated by
                           reference herein.

                  4.2      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, which is
                           incorporated herein by reference.

                  4.3      The Input/Output, Inc. 2003 Employee Stock Option
                           Plan.

                  5.1      Opinion of Fulbright & Jaworski L.L.P.

                  23.1     Consent of PricewaterhouseCoopers LLP.

                  23.2     Consent of KPMG LLP.

                  23.3     Consent of Fulbright & Jaworski L.L.P. (included in
                           their opinion filed as Exhibit 5.1).

                  24.1     Powers 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;

                  (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 hereof) which, individually or in the aggregate,
represent a fundamental change in the information set forth in this Registration
Statement; and

                                      II-4
<PAGE>

                  (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 (i) and (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 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, each such post-effective amendment shall be deemed to be a new
registration statement relating to the securities offered herein, 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, 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 this Registration Statement
shall be deemed to be a new registration statement relating to the securities
offered herein, 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 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 Securities and Exchange Commission
such indemnification is against public policy as expressed in the Securities Act
and is, therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the Registrant of expenses
incurred or paid by a director, officer or controlling person of the Registrant
in the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.

                                      II-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 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 Stafford, State of Texas, on February 10,
2004.

                               INPUT/OUTPUT, INC.

                               By:         /s/ Robert P. Peebler
                                  ---------------------------------------------
                                            Robert P. Peebler
                               President, Chief Executive Officer and Director

                                POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS, that each individual whose signature appears
below constitutes and appoints Robert P. Peebler and J. Michael Kirksey, and
each of them, his true and lawful attorneys-in-fact and agents, with full power
of substitution and resubstitution for him and in his name, place and stead, in
any and all capacities, to sign, execute and file this registration statement
under the Securities Act and any and all amendments (including, without
limitation, post-effective amendments and any amendment or amendments or
additional registration statement filed pursuant to Rule 462 under the
Securities Act increasing the amount of securities for which registration is
being sought) to this registration statement, and to file the same, with all
exhibits thereto, and any and all other documents in connection therewith, with
the Securities and Exchange Commission, to sign any and all applications,
registration statements, notices or other documents necessary or advisable to
comply with the applicable state securities laws, and to file the same, together
with other documents in connection therewith, with the appropriate state
securities authorities, granting unto said attorney-in-fact and agents full
power and authority to do and perform each and every act and thing requisite and
necessary to be done, as fully to all intents and purposes as 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 hereof.

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

<TABLE>
<CAPTION>
         SIGNATURE                                       TITLE                                 DATE
-----------------------------           --------------------------------------          -------------------
<S>                                     <C>                                             <C>
    /s/ Robert P. Peebler               President, Chief Executive Officer and
-----------------------------           Director (principal executive officer)          February 10, 2004
      Robert P. Peebler

                                             Executive Vice President
   /s/ J. Michael Kirksey                    and Chief Financial Officer                February 10, 2004
-----------------------------              (principal financial officer)
     J. Michael Kirksey
</TABLE>

                                      II-6
<PAGE>

<TABLE>
<S>                                      <C>                                            <C>
   /s/ Michael L. Morrison               Controller and Director of Accounting          February 10, 2004
-----------------------------               (prinicipal accounting officer)
     Michael L. Morrison

  /s/ James M. Lapeyre, Jr.                    Chairman of the Board of                 February 10, 2004
-----------------------------                    Directors and Director
    James M. Lapeyre, Jr.

   /s/ Bruce S. Applebaum                              Director                         February 10, 2004
-----------------------------
  Bruce S. Appelbaum, Ph.D

/s/ Theodore H. Elliott, Jr.                           Director                         February 10, 2004
-----------------------------
  Theodore H. Elliott, Jr.

     /s/ Franklin Myers                                Director                         February 10, 2004
-----------------------------
       Franklin Myers

      /s/ John N. Seitz                                Director                         February 10, 2004
-----------------------------
        John N. Seitz

     /s/ Sam K. Smith
-----------------------------
        Sam K. Smith                                   Director                         February 10, 2004
</TABLE>

                                      II-7
<PAGE>

                                INDEX TO EXHIBITS

                  4.1      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, which
                           is incorporated by reference herein, as amended by
                           the First Amendment to Rights Agreement, dated as of
                           April 21, 1999, by and between the Company and Harris
                           Trust and Savings Bank, as Rights Agent, filed as
                           Exhibit 10.3 to the Company's Current Report on Form
                           8-K filed on May 7, 1999, which is incorporated by
                           reference herein.

                  4.2      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, which is
                           incorporated herein by reference.

                  4.3      The Input/Output, Inc. 2003 Employee Stock Option
                           Plan.

                  5.1      Opinion of Fulbright & Jaworski L.L.P.

                  23.1     Consent of PriceWaterhouseCoopers LLP.

                  23.2     Consent of KPMG LLP.

                  23.3     Consent of Fulbright & Jaworski L.L.P. (included in
                           their opinion filed as Exhibit 5.1).

                  24.1     Powers of Attorney (included on the signature page
                           hereto).
[{"type": "S-8", "sequence": "1", "filename": "h12477sv8.txt", "description": "INPUT/OUTPUT, INC.", "secsgml_size_bytes": 21521}]
{"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": "333-112677", "film-number": "04582964"}, "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 FEBRUARY 10, 2004

                              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 PARC CREST DR.
                              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. 2003 EMPLOYEE STOCK OPTION PLAN
                              (FULL TITLE OF PLAN)

                               J. MICHAEL KIRKSEY
                       EXECUTIVE VICE PRESIDENT AND CHIEF
                                FINANCIAL OFFICER
                               INPUT/OUTPUT, INC.
                              12300 PARC CREST DR.
                              STAFFORD, TEXAS 77477
                                 (281) 933-3339

       (NAME, ADDRESS, INCLUDING ZIP CODE, AND TELEPHONE NUMBER, INCLUDING
                        AREA CODE, OF AGENT FOR SERVICE)

                                 WITH COPIES TO:
                           FULBRIGHT& JAWORSKI L.L.P.
                            1301 MCKINNEY, SUITE 5100
                              HOUSTON, TEXAS 77010
                          ATTENTION: MARC H. FOLLADORI
                                 (713) 651-5151

                         CALCULATION OF REGISTRATION FEE
==========================================================================================================
                                                 PROPOSED            PROPOSED MAXIMUM
TITLE OF SECURITIES       AMOUNT TO           MAXIMUM OFFERING      AGGREGATE OFFERING        AMOUNT OF
TO BE REGISTERED      BE REGISTERED(1)(2)    PRICE PER SHARE(2)          PRICE(2)         REGISTRATION FEE
----------------------------------------------------------------------------------------------------------
Common Stock
 $.01 par value        1,500,000 shares          $5.17                 $7,755,000.00           $982.56
==========================================================================================================
(1)     Pursuant to Rule 416(a), 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. 2003 Employee Stock
        Option Plan (the "Plan").

(2)     The 1,500,000 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 February 5, 2004 as reported on
        the New York Stock Exchange composite tape.

================================================================================
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:

         -        The Company's Annual Report on Form 10-K for the year ended
                  December 31, 2002;

         -        The Company's Quarterly Reports on Form 10-Q for the quarters
                  ended March 31, 2003, June 30, 2003 September 30, 2003, and on
                  Form 10-Q/A for the quarters ended June 30 and September 30,
                  2003;

         -        The Company's Current Reports on Form 8-K filed on March 31,
                  April 17, December 4, December 5 and December 17, 2003;

         -        The description of the Company's common stock contained in the
                  Company's registration statement on Form 8-A dated October 14,
                  1994 filed under Section 12(b) of the Exchange Act, as amended
                  by the Company's Current Report on Form 8-K filed on March 8,
                  2002; and

         -        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-A12B filed on
                  January 27, 1997, as amended by the Company's amended
                  registration statement on Form 8-A12B/A filed on 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 of such documents.

ITEM 4.  DESCRIPTION OF SECURITIES

         Not Applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.

         Not Applicable.

                                      II-2
ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         The General Corporation Law of the State of Delaware ("DGCL") permits
the Company and its stockholders to limit directors' exposure to liability for
certain breaches of the directors' fiduciary duty, either in a suit on behalf of
the Company or in an action by stockholders of the Company. The Certificate of
Incorporation of the Company (the "Charter") provides that a director of the
Company shall not be personally liable to the Company or its stockholders for
monetary damages for breach of fiduciary duty as a director, except for
liability (i) for any breach of the director's duty of loyalty to the Company or
its stockholders, (ii) for acts or omissions not in good faith or which involve
intentional misconduct or a knowing violation of law, (iii) under Section 174 of
the General Corporation Law of the State of Delaware, or (iv) for any
transaction from which the director derived an improper personal benefit.

         The Amended and Restated Bylaws (the "Bylaws") of the Company provide
that the Company shall, to the full extent permitted by applicable laws
(including the DGCL), indemnify its directors, officers, employees and agents
with respect to expenses (including counsel fees), judgments, fines, penalties,
other liabilities and amounts incurred by any such person in connection with any
threatened, pending or completed action, suit or proceeding to which such person
is or was a party, or is or was threatened to be made a party, by reason of the
fact that such person is or was serving as a director, officer, employee or
agent of the Company or any of its subsidiaries, or is or was serving at the
request of the Company or any of its subsidiaries as a director, officer,
employee, agent or trustee of another corporation, partnership, joint venture,
trust, employee benefit plan or other enterprise. The Bylaws provide that the
indemnification provided pursuant to the Bylaws is not exclusive of any other
rights to which those seeking indemnification may be entitled under any
provision of law, certificate of incorporation, bylaws, governing documents,
agreement, vote of stockholders or disinterested directors or otherwise. The
Company has entered into indemnification agreements with each of its officers
and directors and intends to enter into indemnification agreements with each of
its future officers and directors. Pursuant to such indemnification agreements,
the Company has agreed to indemnify its officers and directors against certain
liabilities.

         The Company maintains a standard form of officers' and directors'
liability insurance policy which provides coverage to the officers and directors
of the Company for certain liabilities, including certain liabilities which may
arise out of this Registration Statement.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

         Not applicable.

                                      II-3
ITEM 8. EXHIBITS

                  4.1      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, which
                           is incorporated by reference herein, as amended by
                           the First Amendment to Rights Agreement, dated as of
                           April 21, 1999, by and between the Company and Harris
                           Trust and Savings Bank, as Rights Agent, filed as
                           Exhibit 10.3 to the Company's Current Report on Form
                           8-K filed on May 7, 1999, which is incorporated by
                           reference herein.

                  4.2      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, which is
                           incorporated herein by reference.

                  4.3      The Input/Output, Inc. 2003 Employee Stock Option
                           Plan.

                  5.1      Opinion of Fulbright & Jaworski L.L.P.

                  23.1     Consent of PricewaterhouseCoopers LLP.

                  23.2     Consent of KPMG LLP.

                  23.3     Consent of Fulbright & Jaworski L.L.P. (included in
                           their opinion filed as Exhibit 5.1).

                  24.1     Powers 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;

                  (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 hereof) which, individually or in the aggregate,
represent a fundamental change in the information set forth in this Registration
Statement; and

                                      II-4
(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 (i) and (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 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, each such post-effective amendment shall be deemed to be a new
registration statement relating to the securities offered herein, 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, 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 this Registration Statement
shall be deemed to be a new registration statement relating to the securities
offered herein, 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 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 Securities and Exchange Commission
such indemnification is against public policy as expressed in the Securities Act
and is, therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the Registrant of expenses
incurred or paid by a director, officer or controlling person of the Registrant
in the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.

                                      II-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 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 Stafford, State of Texas, on February 10,
2004.

                               INPUT/OUTPUT, INC.

                               By:         /s/ Robert P. Peebler
                                  ---------------------------------------------
                                            Robert P. Peebler
                               President, Chief Executive Officer and Director

                                POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS, that each individual whose signature appears
below constitutes and appoints Robert P. Peebler and J. Michael Kirksey, and
each of them, his true and lawful attorneys-in-fact and agents, with full power
of substitution and resubstitution for him and in his name, place and stead, in
any and all capacities, to sign, execute and file this registration statement
under the Securities Act and any and all amendments (including, without
limitation, post-effective amendments and any amendment or amendments or
additional registration statement filed pursuant to Rule 462 under the
Securities Act increasing the amount of securities for which registration is
being sought) to this registration statement, and to file the same, with all
exhibits thereto, and any and all other documents in connection therewith, with
the Securities and Exchange Commission, to sign any and all applications,
registration statements, notices or other documents necessary or advisable to
comply with the applicable state securities laws, and to file the same, together
with other documents in connection therewith, with the appropriate state
securities authorities, granting unto said attorney-in-fact and agents full
power and authority to do and perform each and every act and thing requisite and
necessary to be done, as fully to all intents and purposes as 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 hereof.

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the dates indicated.
SIGNATURE                                       TITLE                                 DATE
-----------------------------           --------------------------------------          -------------------
/s/ Robert P. Peebler               President, Chief Executive Officer and
-----------------------------           Director (principal executive officer)          February 10, 2004
      Robert P. Peebler

                                             Executive Vice President
   /s/ J. Michael Kirksey                    and Chief Financial Officer                February 10, 2004
-----------------------------              (principal financial officer)
     J. Michael Kirksey
II-6
/s/ Michael L. Morrison               Controller and Director of Accounting          February 10, 2004
-----------------------------               (prinicipal accounting officer)
     Michael L. Morrison

  /s/ James M. Lapeyre, Jr.                    Chairman of the Board of                 February 10, 2004
-----------------------------                    Directors and Director
    James M. Lapeyre, Jr.

   /s/ Bruce S. Applebaum                              Director                         February 10, 2004
-----------------------------
  Bruce S. Appelbaum, Ph.D

/s/ Theodore H. Elliott, Jr.                           Director                         February 10, 2004
-----------------------------
  Theodore H. Elliott, Jr.

     /s/ Franklin Myers                                Director                         February 10, 2004
-----------------------------
       Franklin Myers

      /s/ John N. Seitz                                Director                         February 10, 2004
-----------------------------
        John N. Seitz

     /s/ Sam K. Smith
-----------------------------
        Sam K. Smith                                   Director                         February 10, 2004
II-7
INDEX TO EXHIBITS

                  4.1      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, which
                           is incorporated by reference herein, as amended by
                           the First Amendment to Rights Agreement, dated as of
                           April 21, 1999, by and between the Company and Harris
                           Trust and Savings Bank, as Rights Agent, filed as
                           Exhibit 10.3 to the Company's Current Report on Form
                           8-K filed on May 7, 1999, which is incorporated by
                           reference herein.

                  4.2      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, which is
                           incorporated herein by reference.

                  4.3      The Input/Output, Inc. 2003 Employee Stock Option
                           Plan.

                  5.1      Opinion of Fulbright & Jaworski L.L.P.

                  23.1     Consent of PriceWaterhouseCoopers LLP.

                  23.2     Consent of KPMG LLP.

                  23.3     Consent of Fulbright & Jaworski L.L.P. (included in
                           their opinion filed as Exhibit 5.1).

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