CERTIFICATE OF AMENDMENT
                                          TO
                        RESTATED  CERTIFICATE OF INCORPORATION
                                          OF
                                  INPUT/OUTPUT, INC.

    Input/Output, Inc., a corporation organized and existing under and by
virtue of the General Corporation Law of the State of Delaware (the
"Corporation"),

    DOES HEREBY CERTIFY: That the following amendment of the Restated
Certificate of Incorporation of the Corporation was duly adopted in accordance
with the provisions of Section 242 of the General Corporation Law of the State
of Delaware:

    SECTION 1 of Article FOURTH of the Corporation's Restated Certificate of
    Incorporation be amended so that, as amended, SECTION 1 of Article FOURTH
    shall be and read as follows:

              "SECTION 1.  CAPITALIZATION.  The Corporation is authorized
         to issue one hundred five million (105,000,000) shares of capital
         stock.  One hundred million (100,000,000) of the authorized
         shares shall be common stock, one cent ($0.01) par value each
         ("Common Stock"), and five million (5,000,000) of the authorized
         shares shall be preferred stock, one cent ($0.01) par value each
         ("Preferred Stock").
    
              Each holder of shares of capital stock of the Corporation
         shall at every meeting of the stockholders be entitled to one
         vote in person or by proxy for each share of the capital stock of
         the Corporation held by the stockholder, unless otherwise
         specifically provided pursuant to this Restated Certificate of
         Incorporation."

    IN WITNESS WHEREOF, the Corporation has caused this certificate to be
signed by Robert P. Brindley, its duly authorized officer, on October 10, 1996.

                                       INPUT/OUTPUT, INC.


                                       By:  /s/  ROBERT. P. BRINDLEY          
                                          ----------------------------------- 
                                          Robert P. Brindley
                                          Senior Vice President, Chief 
                                          Financial Officer and Secretary