Exhibit 32.1


                            Certification Pursuant to
                             18 U.S.C. Section 1350,
                             As Adopted Pursuant to
                  Section 906 of the Sarbanes-Oxley Act of 2002

In connection with the Annual Report of O.I. Corporation (the "Company") on Form
10-K for the period ended December 31, 2004, as filed with the Securities and
Exchange Commission on the date hereof (the "Report"), I, William W. Botts,
President and Chief Executive Officer of the Company, certify, pursuant to 18
U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley
Act of 2002, that to my knowledge:

      (1)  The Report fully complies with the requirements of Section 13(a) or
           15(d) of the Securities Exchange Act of 1934; and

      (2)  The information contained in the Report fairly presents, in all
           material respects, the financial condition and results of operations
           of the Company.

This certification is made solely pursuant to Section 906 of the Sarbanes-Oxley
Act of 2002, and not for any other purpose.

A signed original of this written statement required by Section 906 has been
provided to O.I. Corporation and will be retained by O.I. Corporation and
furnished to the Securities and Exchange Commission or its staff upon request.


/s/ William W. Botts
--------------------------------------------
Name:   William W. Botts
Title:  President and Chief Executive Officer
Date:   March 23, 2005