UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                               FORM 13F COVER PAGE

Report for the Calendar Year or Quarter Ended: March 31, 2001

Check here if Amendment [  ]; Amendment Number: _____
   This Amendment (Check only one.): [   ]  is a restatement.
                                     [   ]  adds new holdings entries.
Institutional Investment Manager Filing this Report:

Name:             International Specialty Products Inc.
Address:          300 Delaware Avenue
                  Wilmington, Delaware  19801

Form 13F File Number:  28-5874

The institutional investment manager filing this report and the person by whom
it is signed hereby represent that the person signing the report is authorized
to submit it, that all information contained herein is true, correct and
complete, and that it is understood that all required items, statements,
schedules, lists, and tables, are considered integral parts of this form.

Person Signing this Report on Behalf of Reporting Manager:

Name:             Richard A. Weinberg
Title:            Executive Vice President and General Counsel
Phone:            973-628-3520

Signature, Place, and Date of Signing:

 /s/ Richard A. Weinberg      Wayne, New Jersey        May 11, 2001
----------------------------  ------------------- ---------------------
[Signature]                      [City, State]            [Date]

Report Type (Check only one.):

[X] 13F HOLDINGS REPORT. (Check here if all holdings of this reporting
    manager are reported in this report.)

[ ] 13F NOTICE. (Check here if no holdings reported are in this report, and
    all holdings are reported by other reporting manager(s).)

[ ] 13F COMBINATION REPORT. (Check here if a portion of the holdings for
    this reporting manager are reported in this report and a portion are
    reported by other reporting manager(s).)






                              Form 13F SUMMARY PAGE

Report Summary:


Number of Other Included Managers:                             1

Form 13F Information Table Entry Total:                        1

Form 13F Information Table Value Total:                 $139,242
                                                       (thousands)

Confidential information has been omitted and filed with the Commission in
accordance with Rule 24b-2 and Form 13F.

List of Other Included Managers:

Provide a numbered list of the name(s) and Form 13F file number(s) of all
institutional investment managers with respect to which this report is filed,
other than the manager filing this report.

No.               Form 13F File Number                      Name
---               --------------------                      ----

1                        28-7274                   ISP Opco Holdings Inc.





                                 NAME OF REPORTING PERSON:  INTERNATIONAL SPECIALTY PRODUCTS INC.



Column 1            Column 2     Column 3     Column 4       Column 5       Column 6      Column 7             Column 8

                      Title                                   Shares
                       Of                      Value            or         Investment       Other        Voting Authority
Name of Issuer        Class       CUSIP      (x $1,000)      Prin Amt      Discretion     Managers    Sole    Shared     None
--------------        -----       -----      ----------      --------      ----------     --------    ----    ------     ----
                                                                                        
Hercules Inc.          COM      427056106       139,242    10,719,200 SH    DEFINED           1              10,719,200


                              Column Total      139,242

Pursuant to the Instructions to Form 13F, holdings of fewer than 10,000 shares
and less than $200,000 aggregate fair market value have not been reported.