<PAGE>
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D. C. 20549

                                   FORM 10-K/A

                                  ANNUAL REPORT
                       PURSUANT TO SECTION 13 OR 15(D) OF
                       THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2002        Commission file number 1-496

                              HERCULES INCORPORATED

                             A DELAWARE CORPORATION
                  I.R.S. EMPLOYER IDENTIFICATION NO. 51-0023450
                                 HERCULES PLAZA
                            1313 NORTH MARKET STREET
                         WILMINGTON, DELAWARE 19894-0001
                             TELEPHONE: 302-594-5000

           Securities registered pursuant to Section 12(b) of the Act
         (Each class is registered on the New York Stock Exchange, Inc.)

                               Title of each class
                       Common Stock ($25/48 Stated Value)
           8% Convertible Subordinated Debentures due August 15, 2010
 9.42% Trust Originated Preferred Securities ($25 liquidation amount), issued by
                                Hercules Trust I
                     and guaranteed by Hercules Incorporated
                         Preferred Share Purchase Rights

      Indicate by check mark whether the Registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
Registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days. Yes |X| No | |

      Indicate by check mark if disclosure of delinquent filers pursuant to Item
405 of Regulation S-K is not contained herein, and will not be contained, to the
best of Registrant's knowledge, in definitive proxy or information statements in
Part III of this Form 10-K/A or any amendment to this Form 10-K/A. | |

      Indicate by check mark whether the Registrant is an accelerated filer (as
defined by Rule 12b-2 of the Act). Yes |X| No | |

      The aggregate market value of registrant's common stock, $25/48 stated
value ("Common Stock") held by non-affiliates based on the closing price on the
last day of the Company's most recently completed second fiscal quarter, or June
28, 2002, was approximately $1.2 billion.

      As of March 31, 2003, registrant had 109,922,726 shares of Common Stock
outstanding, which is registrant's only class of common stock.

      On the corporate website, www.herc.com, Hercules Incorporated provides
access to the Company's filings with the Securities and Exchange Commission via
a hyperlink to the Commission's website.

<PAGE>

HERCULES INCORPORATED

                                    PART III

EXPLANATORY NOTE

      In Part III of the Form 10-K filed on March 31, 2003, certain disclosures
were incorporated by reference to the Company's Proxy Statement. Due to the fact
that the Company's Proxy Statement will be filed after April 30, 2003, the
information reported in this Form 10-K/A furnishes the disclosures required in
Part III of the Form 10-K.

ITEM 11. EXECUTIVE COMPENSATION

COMPENSATION OF DIRECTORS

      Employee directors receive no compensation for serving on the Board of
Directors or its committees.

      Non-employee directors receive a $30,000 annual fee ($16,000 payable
quarterly in cash installments and $14,000 payable quarterly in Restricted Stock
Units (RSUs)), $1,000 for each meeting attended in person or by telephone,
$3,000 for chairing a committee, $1,000 per day for special assignments and
reimbursement for out-of-pocket expenses. The annual fee was increased from
$16,000 to $30,000 by the Board of Directors in October 2002, effective
immediately. The annual fee for 2002 was prorated based upon the date the fees
were changed.

      Additionally, at the October meeting, the Board of Directors approved
making annual grants of RSUs, the number of which are equal to the value
difference between $45,000 and the value of 3,000 stock options granted under
the Non-Employee Director Stock Accumulation Plan as discussed below and valued
using the Black-Scholes option-pricing model.

      NON-EMPLOYEE DIRECTOR STOCK ACCUMULATION PLAN. In 2002, as in past years,
non-employee directors had the right to elect to receive restricted stock or
equivalent options in lieu of part or all of their fees under Hercules'
Non-Employee Director Stock Accumulation Plan (the "NEDSAP"). Restricted stock
issued pursuant to the NEDSAP is restricted until the director's retirement from
the Board of Directors and is valued at 85% of the fair market value of the
Company's common stock. Options issued pursuant to the NEDSAP are valued using
the Black-Scholes formula.

      Under the NEDSAP, each director also receives an annual nonqualified stock
option to purchase 3,000 shares of common stock. The option exercise price is
the fair market value of Hercules' common stock on the date of grant. Vesting
occurs one year from the grant date.

      EQUITY AWARD. Each director has a one-time opportunity to purchase 750
Hercules common shares at fair market value when first elected to the Board of
Directors. Upon the purchase, Hercules awards an additional 1,500 Hercules
common shares that cannot be transferred until retirement or resignation from
the Board of Directors.

      RESTRICTED STOCK UNIT GRANT. Upon being elected to the Board of Directors,
each director receives 1,100 restricted stock units. The units are placed in an
unfunded account and accrue dividend equivalents, to the extent any dividends
are paid on the Company's common stock. Each restricted stock unit represents
the right to receive one Hercules common share at retirement. Restricted stock
units do not carry any voting rights. Of the 1,100 units, 200 vest immediately.
Thereafter, for every year served on the Board of Directors, 100 additional
units vest. Upon retirement from the Board of Directors, all vested restricted
stock units are paid in Hercules common shares. This payout will be made in a
lump sum or spread over a period not to exceed ten years, as elected by the
director.

TRUST ARRANGEMENTS

      The Company has previously established a Trust (sometimes referred to as
a "Rabbi Trust") to provide for the funding of accrued benefits under the
Hercules Incorporated Retirement Plan for Nonemployee Directors and the
Hercules Incorporated Deferred Compensation Plan for Nonemployee Directors that
are currently not funded. Under the terms of the Trust, the funding is
triggered by an "Unsolicited Change in Control Event" as defined therein. A
copy of the Trust is filed as an exhibit hereto. Management intends to
recommend to the Board of Directors that the Trust be amended to provide, among
other things, for a substantial reduction in the funding that would be required
should such funding be triggered.

COMPENSATION COMMITTEE INTERLOCKS AND INSIDER PARTICIPATION

      The Compensation Committee is currently composed of four members. Through
June 2002, Mr. McCausland served as Chairman of the Compensation Committee with
Mr. Lipton, Ms. Holiday and Ms. Sneed. Mr. Drosdick also served on the
Compensation Committee until his retirement in April 2002. In June 2002, Mr.
Lipton became Chairman of the Compensation Committee and served with Ms.
Holiday, Mr. Troubh and Ms. Sneed until her resignation from the Board of
Directors in October 2002. Presently, the Compensation Committee consists of
Messrs. Hunter, Lipton (Chairman), Troubh and Ms. Holiday. None of the members
of the Compensation Committee is an officer, employee or former officer or
employee of the Company or its subsidiaries. In 2002, none of the members of the
Compensation Committee had any relationship requiring disclosure in accordance
with Item 402(j)(3) of Regulation S-K.


                                       2
<PAGE>

HERCULES INCORPORATED

COMPENSATION OF EXECUTIVE OFFICERS

      The following table contains information concerning compensation paid or
to be paid to those serving as Chief Executive Officer and the other four most
highly compensated executive officers of the Company for services rendered to
the Company and its subsidiaries during the past three completed fiscal years.

                           SUMMARY COMPENSATION TABLE

<TABLE>
<CAPTION>
                                                                                                 LONG-TERM
                                              ANNUAL COMPENSATION                           COMPENSATION AWARDS
                                              -------------------                           -------------------
                                                       VARIABLE                                               ALL OTHER
                                           SALARY    COMPENSATION                 RESTRICTED     OPTIONS    COMPENSATION
                                  YEAR       $           (4) $      OTHER ($)     STOCK (6)($)   (SHARES)      (7) ($)
                                  ----       -             -        ---------     ------------   --------      -------
<S>                               <C>    <C>         <C>           <C>            <C>            <C>        <C>
W. H. Joyce (1)                   2002   $1,000,000   $1,930,000   $   30,084      $       --      600,000   $   54,619
Chairman and Chief Executive      2001      666,667      997,500        5,662              --    1,250,000       10,126
Officer                           2000           --           --           --              --           --           --

F. G. Aanonsen (2)                2002      260,000      250,000        8,473              --       50,000        4,737
Vice President and Controller     2001      130,000      175,000           --              --       35,500          650
                                  2000           --           --           --              --           --           --

R. G. Dahlen (3)                  2002      300,000      259,000           --              --       50,000       12,460
Chief Legal Officer               2001      163,095      150,000           --              --       35,500      587,484
                                  2000           --           --           --              --           --           --

R. C. Flexon                      2002      257,920      260,000           --              --       50,000       11,615
Vice President, Work Processes,   2001      248,000      175,000           --              --       35,500        5,100
Corporate Resources and           2000      138,182           --       58,181(5)       93,750       30,700        3,000
Development

C. A. Rogerson                    2002      267,082      281,000        8,335(5)           --       50,000       12,482
Vice President and                2001      257,928      200,000        4,631(5)           --       35,500        7,772
General Manager,                  2000      157,614           --      114,742(5)           --       45,500        4,375
FiberVisions and Pinova
</TABLE>

(1)   Dr. Joyce became Chief Executive Officer on May 8, 2001. Dr. Joyce's
      "Other" column includes taxes paid by the Company.

(2)   Mr. Aanonsen was hired as Vice President and Controller on July 2, 2001.
      Mr. Aanonsen's "Other" column includes taxes paid by the Company.

(3)   Mr. Dahlen was rehired as Chief Legal Officer on June 15, 2001. Prior to
      Mr. Dahlen being rehired, he was engaged as a consultant to Hercules. As a
      result of this consulting agreement, Mr. Dahlen was paid $270,000, which
      is reflected in the 2001 total in the "All Other Compensation" column.
      Additionally, included in this total is $307,509 as full settlement of
      payments owed to Mr. Dahlen as a result of his previous Hercules
      employment and $9,975 of other compensation, which was primarily the
      Company's matching contribution and interest on defined contribution
      plans.

(4)   The 2002 variable compensation was awarded in March 2003 for services
      rendered in 2002.

(5)   Messrs. Rogerson and Flexon's "Other" columns include taxes and relocation
      expenses paid by the Company.

(6)   These values are determined by multiplying the number of shares of
      restricted stock awarded by the closing market price of Hercules common
      stock on the date of grant and subtracting the consideration, if any, paid
      by the executive officer. Dividends, if any are payable, may be paid on a
      current basis or accrued. The number and value (determined by taking the
      number of shares of restricted stock multiplied by the year-end closing
      market price, or $8.80, net of any consideration paid) of aggregate
      restricted stock holdings is shown below. Included in the chart are
      restricted shares that each executive officer purchased under the terms of
      the Hercules Long-Term Incentive Compensation Plan, reported in the column
      entitled "Above Target MICP Grant," as well as shares that have been
      granted outright, which are reported in


                                       3
<PAGE>

HERCULES INCORPORATED

the column entitled "Restricted Stock Grant." The aggregate amount paid for
restricted shares by executive officers was $424,419.

<TABLE>
<CAPTION>
                        Above Target MICP Grant             Restricted Stock Grant
                      ---------------------------         ---------------------------
                      Aggregate                           Aggregate
                      Restricted         12/31/02         Restricted         12/31/02
                        Shares          Net Value           Shares          Net Value
                      ----------        ---------         ----------       ----------
<S>                   <C>               <C>               <C>              <C>
W. H. Joyce               24,509               --                --                --
F. G. Aanonsen             1,881               --                --                --
R. G. Dahlen               3,713               --                --                --
R. C. Flexon               4,971               --             5,000        $   44,000
C. A. Rogerson             6,956               --                --                --
</TABLE>

(7)   The amounts listed in the "All Other Compensation" column for 2002 reflect
      the Company's matching contribution and interest on both the qualified and
      non-qualified defined contribution plans.

OPTION GRANTS IN LAST FISCAL YEAR

      The following table discloses information concerning individual grants of
stock options made during the last completed fiscal year to the executive
officers named in the summary compensation table.

<TABLE>
<CAPTION>
                                         Percent of
                   No. of Securities    Total Options      Exercise or
                      Underlying          Granted to        Base Price   Expiration     Grant       Grant Date
     Name          Options Granted        Employees         ($/Share)       Date         Date        Value (1)
----------------   -----------------    -------------     -------------  ----------    --------     ------------
<S>                <C>                  <C>               <C>            <C>           <C>          <C>
W. H. Joyce           600,000(2)            29.5%           $    11.91    5/9/2012     5/9/2002     $ 3,069,240
F. G. Aanonsen         50,000(2)             2.5%                11.91    5/9/2012     5/9/2002         255,770
R. G. Dahlen           50,000(2)             2.5%                11.91    5/9/2012     5/9/2002         255,770
R. C. Flexon           50,000(2)             2.5%                11.91    5/9/2012     5/9/2002         255,770
C. A. Rogerson         50,000(2)             2.5%                11.91    5/9/2012     5/9/2002         255,770
</TABLE>

(1)   The Black-Scholes option-pricing model was used to determine the fair
      value of employee stock options in the table above as of the date of the
      grant. No adjustments for risk of forfeiture have been made. Significant
      assumptions are as follows:

      Dividend yield                     0.0%
      Risk free interest rate            5.0%
      Expected life                      6 years
      Expective volatility               34.6%

      In the fourth quarter of 2000, the Board of Directors approved suspension
      of the Hercules common stock dividend. During the period from January 1,
      1997 to December 31, 2002, the dividend yield on Hercules common stock
      averaged 2.03%. Had the stock options been valued using the historical
      dividend yield in the Black-Scholes option-pricing model, the value of Dr.
      Joyce's grant would have been $2,449,740. Other grants reported herein
      would be similarly adjusted downward.

(2)   Vesting schedule is as follows: 40% on 5/9/03; 40% on 5/10/04; and 20% on
      5/9/05. Options are immediately vested and exercisable upon retirement and
      remain exercisable for a period of five years. Dr. Joyce and Mr. Dahlen
      are both currently eligible to retire.


                                       4
<PAGE>

HERCULES INCORPORATED

AGGREGATED OPTION EXERCISES IN LAST FISCAL YEAR AND FISCAL YEAR-END OPTION
VALUES

      The table set forth below discloses certain information concerning the
exercise of stock options (exercised and unexercised) during the last completed
fiscal year by the executive officers named in the summary compensation table as
well as certain information concerning the number and value of unexercised
options. The value of options is calculated using the difference between the
option exercise price and $8.80 (year-end stock price) multiplied by the number
of shares underlying the option.

<TABLE>
<CAPTION>
                         No. of                            No. of Securities                   Value of Unexercised
                         Shares          Value          Underlying Unexercised                 In-The-Money Options
                        Acquired       Realized           Options at Year-End                      At Year-End
Name                   on Exercise         $          Exercisable     Unexercisable     Exercisable ($)    Unexercisable ($)
------------------    ------------    -----------     -----------     -------------     ---------------    -----------------
<S>                   <C>             <C>             <C>             <C>               <C>                <C>
W. H. Joyce                0             0                   0        1,850,000               $0                 $0
F. G. Aanonsen             0             0              14,200           71,300                0                  0
R. G. Dahlen               0             0             138,200          167,300                0                  0
R. C. Flexon               0             0              38,760           77,440                0                  0
C. A. Rogerson             0             0              50,600           80,400                0                  0
</TABLE>


                                       5
<PAGE>

HERCULES INCORPORATED

PENSION PLANS

      The following table shows the estimated annual pension benefits payable to
a covered participant at normal retirement age under Hercules' qualified
benefits pension plan, as well as nonqualified supplemental benefits, based on
the stated remuneration and years of service with Hercules and its subsidiaries.

<TABLE>
<CAPTION>
REMUNERATION      15 YEARS        20 YEARS        25 YEARS        30 YEARS          35 YEARS
------------      --------        --------        --------        --------          --------
<S>               <C>             <C>             <C>             <C>             <C>
$  200,000        $ 45,453        $ 60,604        $ 75,755        $ 90,906        $  106,057
   250,000          57,453          76,604          95,755         114,906           134,057
   300,000          69,453          92,604         115,755         138,906           162,057
   350,000          81,453         108,604         135,755         162,906           190,057
   400,000          93,453         124,604         155,755         186,906           218,057
   450,000         105,453         140,604         175,755         210,906           246,057
   500,000         117,453         156,604         195,755         234,906           274,057
   600,000         141,453         188,604         235,755         282,906           330,057
   700,000         165,453         220,604         275,755         330,906           386,057
   800,000         189,453         252,604         315,755         378,906           442,057
   900,000         213,453         284,604         355,755         426,906           498,057
 1,000,000         237,453         316,604         395,755         474,906           554,057
 1,500,000         357,453         476,604         595,755         714,906           834,057
 2,000,000         477,453         636,604         795,755         954,906         1,114,057
</TABLE>

      Annual contributions by Hercules to its qualified pension plan, if any are
required, are determined statistically by an independent actuary, and no amount
is attributed to an individual employee. In 2002, the Company contributed $97
million to the Company's pension plans.

      Generally, the aggregate annual retirement benefit, under both the
qualified and nonqualified plans, is an amount determined by taking the sum of
(i) 1.2% of the employee's average annual earnings (based on the highest five
consecutive years during the last 10 years of employment) up to one-half the
Social Security Tax Base ($42,450 in 2002), and (ii) 1.6% of the employee's
average annual earnings (as determined above) in excess of one-half of the
Social Security Tax Base, multiplied by the employee's total years and months of
credited service. For this purpose, "average annual earnings" consists of salary
plus annual incentive or variable compensation. Certain exceptions apply to
union represented employees.

      For Dr. Joyce and Messrs. Aanonsen, Dahlen, Flexon and Rogerson,
compensation used for calculating retirement income benefits consists of the
highest 5 consecutive years of average annual earnings. These amounts for 2002
are shown under the "Salary" and "Variable Compensation" columns of the Summary
Compensation Table. The estimated credited years of service for Dr. Joyce and
Messrs. Aanonsen, Dahlen, Flexon and Rogerson are 1, 1, 8, 2 and 20,
respectively.

TRUST ARRANGEMENTS

     The Company has previously established a Trust (sometimes referred to as a
"Rabbi Trust") to provide for the funding of accrued benefits under the
Hercules Incorporated Deferred Compensation Plan, the Hercules Incorporated
Non-qualified Supplemental Retirement Plan, the Hercules Incorporated Phantom
Stock Plan and other retirement income or employment agreements that are
currently not funded. Under the terms of the Trust, the funding is triggered by
an "Unsolicited Change in Control Event" as defined therein. A copy of the
Trust is filed as an exhibit hereto. Management intends to recommend to the
Board of Directors that the Trust be amended to provide, among other things,
for a substantial reduction in the funding that would be required should such
funding by triggered.

EMPLOYMENT CONTRACTS

      On May 8, 2001, Hercules entered into a two-year written employment
agreement with Dr. Joyce which provides for him to serve as Chairman and Chief
Executive Officer. Under the agreement, Dr. Joyce's initial compensation
consisted of (i) a base annual salary of $1,000,000, (ii) target annual variable
compensation of $1,000,000 and (iii) a grant of stock options to acquire
1,250,000 shares of common stock at a per share exercise price of $12.00 (the
price of Hercules' common stock on the date of grant). The stock options have
ten-year terms and vest at the earliest of April 30, 2003, a "change in
control", death, disability or termination other than for cause. Dr. Joyce's
employment agreement also provides for further grants of stock options for each
calendar year after 2001, at such times as Hercules generally makes stock option
grants to other employees and in amounts and with terms and conditions
consistent with his position.


                                       6
<PAGE>

HERCULES INCORPORATED

CHANGE IN CONTROL AGREEMENTS

      Since 1986, Hercules has entered into change in control agreements with
its senior executives. These agreements seek to ensure the stability of
Hercules' management during a period of transition within Hercules and only
become effective upon a change in control event. Hercules' Compensation
Committee periodically reviews these agreements and revises them, if necessary,
to reflect contemporary business practices in change in control situations.

      Change in Control Agreements are in force for Dr. Joyce and Messrs.
Aanonsen, Dahlen, Flexon and Rogerson. These Agreements, the form of which has
been filed with the Securities and Exchange Commission, provide that a change in
control occurs:

      -     if any individual, entity or group (with certain exceptions) becomes
            the beneficial owner of 20% or more of the outstanding shares of
            Hercules common stock;

      -     if there is a change in a majority of the Board of Directors other
            than by election or nomination by a vote of the majority of
            directors comprising the incumbent Board of Directors;

      -     upon approval by the shareholders of a reorganization, merger,
            consolidation or sale that results in Hercules' shareholders owning
            less than 60% of the combined voting power of the surviving
            corporation following the transaction; or

      -     if Hercules' shareholders approve a complete liquidation of the
            Company.

      The full definition of change in control is set forth in the Agreements.

      Under the terms of these agreements, upon a change in control, Hercules or
its successor is required to continue to employ the above named executives, in
substantially the same position and level of compensation (including benefits)
as that executive held immediately before the change in control, for a period of
three years following the change in control.

      Under the terms of these agreements, as amended in 2001, if Hercules or
its successor terminates the executive (within the three year period following a
change in control) for any reason other than cause, death or disability, or if
Hercules or its successor takes actions which permit the executive to terminate
his or her employment for good reason, such as diminishing the executive's
responsibilities or requiring the executive to relocate, during such three year
period, the executive is entitled to the following:

      - a lump sum cash payment equal to:

            -     any unpaid prorated portion of the executive's variable
                  compensation or, if greater, the most recent variable
                  compensation received by the executive;

            -     any monthly salary earned but unpaid as of the date of
                  termination;

            -     three times the executive's base salary and variable
                  compensation; and

            -     the difference between the amount the executive would be
                  entitled to if Hercules or its successor contributed to the
                  executive's retirement plan for up to three additional years
                  of service (in addition to the years of service credited
                  during the employment period) and three additional years of
                  age and that amount the executive was actually entitled to
                  under this plan on the date of termination;

      -     three years of continued welfare benefits and perquisites;

      -     outplacement services at a cost of up to $50,000;

      -     full vesting of all stock options and restricted stock held by or
            previously granted to the executive; and

      -     payment for any Internal Revenue Service excise taxes for "excess
            parachute payments" (as defined under the Internal Revenue Code).

      Dr. Joyce's and Mr. Dahlen's change in control agreements also provide
that if they terminate their employment on at least 180 days' advance notice
after a change of control and, in the case of a change in control triggered by
shareholder approval of a reorganization, merger, consolidation or sale
described above, after consummation of that transaction, the termination will be
treated as a termination for good reason, giving rise to the severance pay and
benefits described above. The agreements entered into with Dr. Joyce and Mr.
Dahlen do not provide for the additional pension service or age credits
described above.

      Mr. Dahlen's change in control agreement provides in the case of a change
in control or termination by the Company for good reason for two times base
salary and variable compensation instead of the three times base salary and
variable compensation discussed above.

ITEM 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

BENEFICIAL OWNERSHIP OF COMMON STOCK

      The following table sets forth information, as of March 31, 2003, with
respect to the beneficial ownership of Hercules common shares by:

      -     beneficial owners of more than five percent of Hercules common
            stock,


                                       7
<PAGE>

HERCULES INCORPORATED

      -     each Hercules director and nominee for director,

      -     each of the executive officers named in the Summary Compensation
            Table set forth above, and

      -     all directors, nominees and executive officers of Hercules as a
            group.

      This information is based upon Hercules' records, as well as publicly
available information filed with the Securities and Exchange Commission.

      This beneficial ownership is reported in accordance with the rules of the
SEC, under which a person may be deemed to be the beneficial owner of shares if
that person has or shares the power to vote or dispose of those shares or has
the right to acquire beneficial ownership of those shares within 60 days (for
example, through the exercise of an option). Accordingly, the shares shown in
the table as beneficially owned by certain individuals may include shares owned
by certain members of their respective families. Because of these rules, more
than one person may be deemed to be the beneficial owner of the same shares. The
inclusion of the shares shown in the table is not necessarily an admission of
beneficial ownership of those shares by the person indicated.

<TABLE>
<CAPTION>
                                                                          OPTIONS
                                                        SHARES          EXERCISABLE
                                                     BENEFICIALLY          WITHIN          RESTRICTED        PERCENT OF
NAME                                                   OWNED (1)          60 DAYS        STOCK UNITS (2)     SHARES (3)
--------------------------------------------------   ------------       -----------      ---------------     ----------
<S>                                                  <C>                <C>              <C>                 <C>
DIRECTORS AND OFFICERS
W. H. Joyce, Director and Officer                         157,374         1,490,000                --          1.5%
F. G. Aanonsen, Officer                                    19,576            14,200                --            *
R. G. Dahlen, Officer                                      34,537           254,200                --            *
R. Fairbanks, Director                                     25,949            27,000             2,231            *
R. C. Flexon, Officer                                      29,743            58,760                --            *
S. J. Heyman, Director (4)                              9,900,120             3,000             2,078          9.0%
A. R. Hirsig, Director                                      6,554            12,000             2,078            *
E. E. Holiday, Director                                     3,999            24,000             2,354            *
J. C. Hunter, III, Director                                    --                --             1,100            *
R. D. Kennedy, Director                                    12,250             3,000             2,078            *
S. Kumar, Director                                         20,909             3,000             2,078            *
J. M. Lipton, Director                                     21,865             3,000             2,078            *
P. McCausland, Director                                    20,560            15,000             2,078            *
C. A. Rogerson, Officer                                    28,895            79,700                --            *
G. Schaffer, Director                                       2,750             3,000             2,078            *
R. S. Troubh, Director                                     14,870             3,000             2,078            *
J. B. Wyatt, Director                                       7,010             3,000             2,078            *

All directors and executive officers as a group        10,549,685         2,747,360            24,387         11.8%

5% SHAREHOLDERS
Mario J. Gabelli and related entities (5)              10,218,507                --                --          9.3%
C/o Gabelli Asset Management Inc.
One Corporate Center
Rye, New York 10580

International Specialty Products, Inc                   9,893,700                --                --          9.0%
    and related entities (6)
C/o ISP Management Company, Inc.
1361 Alps Road
Wayne, New Jersey 07670

T. Rowe Price Associates, Inc. (7)                      9,209,934                --                --          8.4%
100 E. Pratt Street
Baltimore, Maryland 21202
</TABLE>


                                       8
<PAGE>

HERCULES INCORPORATED

<TABLE>
<CAPTION>
                                                                          OPTIONS
                                                        SHARES          EXERCISABLE
                                                     BENEFICIALLY          WITHIN          RESTRICTED        PERCENT OF
NAME                                                   OWNED (1)          60 DAYS        STOCK UNITS (2)     SHARES (3)
--------------------------------------------------   ------------       -----------      ---------------     ----------
<S>                                                  <C>                <C>              <C>                 <C>
Vanguard Fiduciary Trust Company (8)                    8,315,904                --                --          7.6%
500 Admiral Nelson Boulevard
Malvern, PA 19355

FMR Corp. and related entities (9)                      7,562,431                --                --          6.9%
82 Devonshire Street
Boston, MA 02109
</TABLE>

*   Less than 1% of the outstanding Hercules common shares.

(1)   Includes shares as of March 31, 2003 in the Hercules Savings and
      Investments Plan as follows: W. H. Joyce, 1,044; F. G. Aanonsen, 686; R.
      G. Dahlen, 3,075; R. C. Flexon, 1,316; C. A. Rogerson, 1,145; and all
      directors and officers as a group, 39,531. Includes shares with
      restrictions and forfeiture risks as specified under the Long Term
      Incentive Compensation Plan; W. H. Joyce, 156,330; F. G. Aanonsen, 18,890;
      R. G. Dahlen, 19,163; R. C. Flexon, 28,427; C. A. Rogerson, 27,750; and
      all directors and officers as a group, 414,208. Owners have the same
      voting and dividend rights as other shareholders of Hercules, but no right
      to sell or transfer. Included in the non-employee directors' totals is a
      one-time equity award.

(2)   The non-employee director does not have any voting rights or the right to
      dispose of these restricted stock units until the non-employee director
      leaves the Board of Directors. Further discussion of this Restricted Stock
      Unit Grant can be found in Part III Item 11 Compensation of Directors in
      this Form 10-K/A filing.

(3)   Based on 109,922,726 shares outstanding on March 31, 2003. The calculation
      of Percent of Shares excludes the share amounts listed in the Restricted
      Stock Units column.

(4)   Includes 9,893,700 shares held by International Specialty Products, Inc.
      ("ISP") and related entities. Mr. Heyman beneficially owns (as defined in
      Rule 13d-3 of the Exchange Act) 100% of the capital stock of ISP and
      therefore may be deemed to beneficially own (solely for purposes of Rule
      13d-3) the Hercules common stock owned by ISP and related entities.

(5)   Share holding as of December 10, 2002, as reported on Amendment No. 6 to
      the Schedule 13D filed by such shareholder on December 12, 2002.

(6)   Share holding as of April 16, 2003, as reported on the preliminary Proxy
      Statement filed by the Hercules Shareholders' Committee for New Management
      on April 16, 2003.

(7)   Share holding as of December 31, 2002, as reported on Amendment No. 4 to
      the Schedule 13G filed by such shareholder on January 31, 2003.

(8)   Share holding as of December 31, 2002, as reported on the Schedule 13G
      filed by such shareholder on April 2, 2003.

(9)   Share holding as of December 31, 2002, as reported on the Scheduled 13G
      filed by such shareholder on February 13, 2003.

                                     PART IV

ITEM 15. EXHIBITS, FINANCIAL STATEMENT SCHEDULES AND REPORTS ON FORM 8-K

            (a) Documents filed as part of this Report:

                  3.    Exhibits:

                        A complete listing of exhibits is included in the
                        Exhibit Index that precedes the exhibits filed with this
                        Report.


                                       9
<PAGE>

HERCULES INCORPORATED

                                   SIGNATURES

      Pursuant to the requirements of Section 13 or 15(d) of the Securities
Exchange Act of 1934, the registrant has duly caused this report to be signed on
its behalf by the undersigned, thereunto duly authorized.

                                      HERCULES INCORPORATED


                                By:   /s/ Fred G. Aanonsen
                                      ---------------------------------------
                                      Fred G. Aanonsen
                                      Vice President and Controller
                                      (Principal Financial Officer and duly
                                      authorized signatory)
                                      April 30, 2003


                                       10
<PAGE>

HERCULES INCORPORATED

                            CERTIFICATION PURSUANT TO
                             18 U.S.C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

I, William H. Joyce, Chairman and Chief Executive Officer, certify that:

1.    I have reviewed this annual report on Form 10-K/A of Hercules
      Incorporated;

2.    Based on my knowledge, this annual report does not contain any untrue
      statement of a material fact or omit to state a material fact necessary to
      make the statements made, in light of the circumstances under which such
      statements were made, not misleading with respect to the period covered by
      this annual report;

3.    Based on my knowledge, the financial statements, and other financial
      information included in this annual report, fairly present in all material
      respects the financial condition, results of operations and cash flows of
      the registrant as of, and for, the periods presented in this annual
      report;

4.    The registrant's other certifying officers and I are responsible for
      establishing and maintaining disclosure controls and procedures (as
      defined in Exchange Act Rules 13a-14 and 15d-14) for the registrant and
      have:

      a)    designed such disclosure controls and procedures to ensure that
            material information relating to the registrant, including its
            consolidated subsidiaries, is made known to us by others within
            those entities, particularly during the period in which this annual
            report is being prepared;

      b)    evaluated the effectiveness of the registrant's disclosure controls
            and procedures as of a date within 90 days prior to the filing date
            of this annual report (the "Evaluation Date"); and

      c)    presented in this annual report our conclusions about the
            effectiveness of the disclosure controls and procedures based on our
            evaluation as of the Evaluation Date;

5.    The registrant's other certifying officers and I have disclosed, based on
      our most recent evaluation, to the registrant's auditors and the audit
      committee of registrant's board of directors (or persons performing the
      equivalent functions):

      a)    all significant deficiencies in the design or operation of internal
            controls which could adversely affect the registrant's ability to
            record, process, summarize and report financial data and have
            identified for the registrant's auditors any material weaknesses in
            internal controls; and

      b)    any fraud, whether or not material, that involves management or
            other employees who have a significant role in the registrant's
            internal controls; and

6.    The registrant's other certifying officers and I have indicated in this
      annual report whether there were significant changes in internal controls
      or in other factors that could significantly affect internal controls
      subsequent to the date of our most recent evaluation, including any
      corrective actions with regard to significant deficiencies and material
      weaknesses.

Date:  April 30, 2003


/s/ William H. Joyce
------------------------------------
William H. Joyce
Chairman and Chief Executive Officer


                                       11
<PAGE>

HERCULES INCORPORATED

                            CERTIFICATION PURSUANT TO
                             18 U.S.C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

I, Fred G. Aanonsen, Vice President and Controller, certify that:

1.    I have reviewed this annual report on Form 10-K/A of Hercules
      Incorporated;

2.    Based on my knowledge, this annual report does not contain any untrue
      statement of a material fact or omit to state a material fact necessary to
      make the statements made, in light of the circumstances under which such
      statements were made, not misleading with respect to the period covered by
      this annual report;

3.    Based on my knowledge, the financial statements, and other financial
      information included in this annual report, fairly present in all material
      respects the financial condition, results of operations and cash flows of
      the registrant as of, and for, the periods presented in this annual
      report;

4.    The registrant's other certifying officers and I are responsible for
      establishing and maintaining disclosure controls and procedures (as
      defined in Exchange Act Rules 13a-14 and 15d-14) for the registrant and
      have:

      a)    designed such disclosure controls and procedures to ensure that
            material information relating to the registrant, including its
            consolidated subsidiaries, is made known to us by others within
            those entities, particularly during the period in which this annual
            report is being prepared;

      b)    evaluated the effectiveness of the registrant's disclosure controls
            and procedures as of a date within 90 days prior to the filing date
            of this annual report (the "Evaluation Date"); and

      c)    presented in this annual report our conclusions about the
            effectiveness of the disclosure controls and procedures based on our
            evaluation as of the Evaluation Date;

5.    The registrant's other certifying officers and I have disclosed, based on
      our most recent evaluation, to the registrant's auditors and the audit
      committee of registrant's board of directors (or persons performing the
      equivalent functions):

      a)    all significant deficiencies in the design or operation of internal
            controls which could adversely affect the registrant's ability to
            record, process, summarize and report financial data and have
            identified for the registrant's auditors any material weaknesses in
            internal controls; and

      b)    any fraud, whether or not material, that involves management or
            other employees who have a significant role in the registrant's
            internal controls; and

6.    The registrant's other certifying officers and I have indicated in this
      annual report whether there were significant changes in internal controls
      or in other factors that could significantly affect internal controls
      subsequent to the date of our most recent evaluation, including any
      corrective actions with regard to significant deficiencies and material
      weaknesses.

Date:  April 30, 2003


/s/ Fred G. Aanonsen
--------------------------------
Fred G. Aanonsen
Vice President and Controller


                                       12
<PAGE>

HERCULES INCORPORATED

EXHIBIT INDEX

<Table>
<Caption>

NUMBER                                DESCRIPTION                                    INCORPORATED BY REFERENCE TO

<S>             <C>                                                             <C>

10-Q            Form of Change-of-Control Employment Agreements entered         Exhibit 10-19, Registration Statement on Form
                into as of August 24, 2000 by Hercules Incorporated and         S-4, filed August 9, 2001
                each of Robert C. Flexon and Craig. A. Rogerson.

10-W            Form of Change-of-Control Employment Agreements entered         Exhibit 10-25, Regtistration Statement on Form
                into as of June 15, 2001 by Hercules Incorporated and           S-4, filed August 9, 2001.
                Richard G. Dahlen.

10-Ee*          Hercules Incorporated Compensation Benefits Grantor
                Trust Agreement for Management Employees.

10-Ff*          Hercules Incorporated Compensation Benefits Grantor
                Trust Agreement for Nonemployee Directors.

10-Gg*          Amended and Restated Hercules Incorporated Management
                Incentive Compensation Plan, dated February 21, 2003.

99.3*           Certification of Chairman and Chief Executive Officer
                Pursuant to 18. U.S.C. Section 1350, as adopted
                pursuant to Section 906 of the Sarbanes-Oxley Act of
                2002

99.4*           Certification of Vice President and Controller Pursuant
                to 18. U.S.C. Section 1350, as adopted pursuant to
                Section 906 of the Sarbanes-Oxley Act of 2002
</Table>

*     Filed herewith


                                       13