<PAGE>

                                                                   EXHIBIT 10.5

                         W. R. GRACE & CO. ("COMPANY")

                           NONSTATUTORY STOCK OPTION

         Under the W. R. Grace & Co. 1998 Stock Incentive Plan ("Plan")


                  Granted To:
                  Date of Grant:                  April 1, 1998
                  Expiration Date:                March 31, 2008


         In accordance with the Plan (a copy of which is attached), you have
been granted an Option to purchase      shares of Common Stock, as defined in 
the Plan ("Option"), upon the following terms and conditions:

         (1) The purchase price is $19.4688 per share.

         (2) Subject to the other provisions hereof, this Option shall become
exercisable as follows:

                            shares on April 2, 1999
                            shares on April 2, 2000
                            shares on April 2, 2001

         Once exercisable, an installment may be exercised at any time, in
whole or in part, until the expiration or termination of this Option.

         (3) This Option shall not be treated as an Incentive Stock Option (as
such term is defined in the Plan.)

         (4) This Option may be exercised only by serving written notice on the
Treasurer of the Company or his designee. The purchase price shall be paid in
cash or, with the permission of the Company (which may be subject to certain
conditions), in shares of Common Stock or in a combination of cash and such
shares (see section 6(a) of the Plan).

         (5) Neither this Option nor and any right thereunder nor any interest
therein may be assigned or transferred by you, except by will or the laws of
descent and distribution. This Option is exercisable during your lifetime only
by you. If you cease to serve the Company or a Subsidiary (as defined in the
Plan), this Option shall terminate as provided in section 6(d) of the Plan,
subject, however, to the following:


THIS DOCUMENT CONSTITUTES PART OF A
PROSPECTUS COVERING SECURITIES THAT
HAVE BEEN REGISTERED UNDER THE
SECURITIES ACT OF 1933.

<PAGE>

                                     - 2 -

              (a)  In the event you should become incapacitated or die and
                   neither you nor your legal representative(s) or other
                   person(s) entitled to exercise this Option exercise this
                   Option to the fullest extent possible on or before its
                   termination, the Company shall pay you, your legal
                   representative(s) or such other person(s), as the case may
                   be, an amount of money equal to the Fair Market Value (as
                   defined under the Plan) of any shares remaining subject to
                   this Option on the last date it could have been exercised,
                   less the aggregate purchase price of such shares.

              (b)  Notwithstanding any provision of the Plan, in the event (i)
                   you voluntarily retire under a retirement plan of the
                   Company or a Subsidiary prior to the date on which the first
                   installment of this Option becomes exercisable and (ii) you
                   do not continue to serve the Company or a Subsidiary until
                   such date, this Option shall terminate as of the date you
                   cease to serve.

         (6) If you are or become an employee of a Subsidiary, the Company's
obligations hereunder shall be contingent on the Subsidiary's agreement that
(a) the Company may administer this Plan on its behalf and, (b) upon the
exercise of this Option, the Subsidiary will purchase from the Company the
shares subject to the exercise at their Fair Market Value on the date of
exercise, such shares to be then transferred by the Subsidiary to you upon your
payment of the purchase price to the Subsidiary. Where appropriate, such
approval and agreement of the Subsidiary shall be indicated by its signature
below. The provisions of this paragraph and the obligations of the Subsidiary
so undertaken may be waived by the Company, in whole or in part, at any time or
from time to time.

         (7) The Plan is hereby incorporated by reference. Terms defined in the
Plan shall have the same meaning herein. This Option is granted subject to the
Plan and shall be construed in conformity with the Plan.

                                            W. R. GRACE & CO.

                                            By /s/ A. J. Costello
                                              ---------------------------------
                                              A. J. Costello, Chairman,
                                              President and CEO
Approved and Agreed to:*

----------------------------------
       (Name of Subsidiary)

By
  --------------------------------
       (Authorized Officer)
                                            RECEIPT ACKNOWLEDGED:


                                            -----------------------------------

* This will be completed only if you are or become an employee of a Subsidiary.

<PAGE>

                         W. R. GRACE & CO. ("COMPANY")

                           NONSTATUTORY STOCK OPTION

         Under the W. R. Grace & Co. 1998 Stock Incentive Plan ("Plan")


                  Granted To:
                  Date of Grant:                  April 1, 1998
                  Expiration Date:                March 31, 2008


         In accordance with the Plan (a copy of which is attached), you have
been granted an Option to purchase       shares of Common Stock, as defined in 
the Plan ("Option"), upon the following terms and conditions:

         (1) The purchase price is $19.4688 per share.

         (2) Subject to the other provisions hereof, this Option shall become
exercisable as follows:

                            shares on April 2, 1999
                            shares on April 2, 2000
                            shares on April 2, 2001

         Once exercisable, an installment may be exercised at any time, in
whole or in part, until the expiration or termination of this Option.

         (3) This Option shall not be treated as an Incentive Stock Option (as
such term is defined in the Plan.)

         (4) This Option may be exercised only by serving written notice on the
Treasurer of the Company or his designee. The purchase price shall be paid in
cash or, with the permission of the Company (which may be subject to certain
conditions), in shares of Common Stock or in a combination of cash and such
shares (see section 6(a) of the Plan).

         (5) Neither this Option nor and any right thereunder nor any interest
therein may be assigned or transferred by you, except by will or the laws of
descent and distribution. This Option is exercisable during your lifetime only
by you. If you cease to serve the Company or a Subsidiary (as defined in the
Plan), this Option shall terminate as provided in section 6(d) of the Plan,
subject, however, to the following:


THIS DOCUMENT CONSTITUTES PART OF A
PROSPECTUS COVERING SECURITIES THAT
HAVE BEEN REGISTERED UNDER THE
SECURITIES ACT OF 1933.

<PAGE>

                                     - 2 -

              (a)  In the event you should become incapacitated or die and
                   neither you nor your legal representative(s) or other
                   person(s) entitled to exercise this Option exercise this
                   Option to the fullest extent possible on or before its
                   termination, the Company shall pay you, your legal
                   representative(s) or such other person(s), as the case may
                   be, an amount of money equal to the Fair Market Value (as
                   defined under the Plan) of any shares remaining subject to
                   this Option on the last date it could have been exercised,
                   less the aggregate purchase price of such shares.

              (b)  Notwithstanding any provision of the Plan, you will have a
                   period of three years after your voluntary retirement under
                   a retirement plan of the Company or a Subsidiary during
                   which you may exercise this Option; however, only the
                   installment(s) that are otherwise exercisable on the date of
                   retirement may be exercised in the event of your voluntary
                   retirement. Any remaining installment(s) will be terminated.

              (c)  Notwithstanding any provision of the Plan, in the event (i)
                   you voluntarily retire under a retirement plan of the
                   Company or a Subsidiary prior to the date on which the first
                   installment of this Option becomes exercisable and (ii) you
                   do not continue to serve the Company or a Subsidiary until
                   such date, this Option shall terminate as of the date you
                   cease to serve.

         (6) If you are or become an employee of a Subsidiary, the Company's
obligations hereunder shall be contingent on the Subsidiary's agreement that
(a) the Company may administer this Plan on its behalf and, (b) upon the
exercise of this Option, the Subsidiary will purchase from the Company the
shares subject to the exercise at their Fair Market Value on the date of
exercise, such shares to be then transferred by the Subsidiary to you upon your
payment of the purchase price to the Subsidiary. Where appropriate, such
approval and agreement of the Subsidiary shall be indicated by its signature
below. The provisions of this paragraph and the obligations of the Subsidiary
so undertaken may be waived by the Company, in whole or in part, at any time or
from time to time.

         (7) The Plan is hereby incorporated by reference. Terms defined in the
Plan shall have the same meaning herein. This Option is granted subject to the
Plan and shall be construed in conformity with the Plan.

                                            W. R. GRACE & CO.

                                            By /s/ A. J. Costello
                                              ---------------------------------
                                              A. J. Costello, Chairman,
                                              President and CEO
Approved and Agreed to:*


----------------------------------
        (Name of Subsidiary)
By                                          RECEIPT ACKNOWLEDGED:
  --------------------------------
        (Authorized Officer)
                                            -----------------------------------

* This will be completed only if you are or become an employee of a Subsidiary.