EXHIBIT 32.1

                   CERTIFICATION OF CEO AND CFO 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 quarterly report on Form 10-Q of ISP Chemco Inc.
(the "Company") for the quarterly period ended October 2, 2005 as filed with the
Securities and Exchange Commission on the date hereof (the "Report"), Sunil
Kumar, as President and Chief Executive Officer of the Company and Roger J.
Cope, as Senior Vice President and Interim Chief Financial Officer of the
Company, each hereby certifies, pursuant to 18 U.S.C. Section 1350, as adopted
pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to the best of
his knowledge and belief:

         (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.


 /s/ Sunil Kumar
- ---------------------------------
Name:   Sunil Kumar
Title:  President and Chief Executive Officer

Date:   November 16, 2005


  /s/ Roger J. Cope
- ---------------------------------
Name:   Roger J. Cope
Title:  Senior Vice President and
          Interim Chief Financial Officer

Date:   November 16, 2005


     This certification accompanies the Report pursuant to Section 906 of the
Sarbanes-Oxley Act of 2002 and shall not, except to the extent required by the
Sarbanes-Oxley Act of 2002, be deemed filed by the Company for purposes of
Section 18 of the Securities Exchange Act of 1934, as amended.