EXHIBIT 99.1

        CERTIFICATION OF CHIEF EXECUTIVE OFFICER PURSUANT TO SECTION 906
                        OF THE SARBANES-OXLEY ACT OF 2002
                            (18 U.S.C. SECTION 1350)

In connection with the Annual Report of Entegris, Inc, a Minnesota corporation
(the "Company"), on Form 10-K for the year ending August 31, 2002 as filed with
the Securities and Exchange Commission (the "Report"), I, James E. Dauwalter,
President and Chief Executive Officer of the Company, certify, pursuant to ss.
906 of the Sarbanes-Oxley Act of 2002 (18 U.S.C. ss. 1350), 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 result of operations of the
Company.



/s/  James E. Dauwalter


James E. Dauwalter
President and Chief Executive Officer