Rule 424(b)(3)
                                                           File No.  333-06955
                             NALCO CHEMICAL COMPANY

                         COMMON STOCK ACQUIRED UNDER THE
                             NALCO CHEMICAL COMPANY
                 NON-EMPLOYEE DIRECTORS STOCK COMPENSATION PLAN
                           APPENDIX DATED MAY 12, 1997
                                       TO
                         PROSPECTUS DATED JUNE 27, 1996

This Appendix updates certain  information in the Prospectus dated June 27, 1996
(the  "Prospectus")  relating to shares of Common  stock which may be offered by
the stockholders  listed herein under the caption  "Selling  Stockholders" or by
their  transferees  (or by their donees or  pledgees).  The Company will furnish
without charge to participants additional copies of the Prospectus upon request.


                              SELLING STOCKHOLDERS

The following  table sets forth the name and position within the Company for the
last three  years of each  Selling  Stockholder,  the number of shares of Common
Stock of the Company  beneficially  owned by him on the date of this  Prospectus
and, the number of shares offered by the Prospectus.

                         Shares Owned                     Shares Offered by
Name of Director         Beneficially (1)                 This Prospectus (2)
- ----------------        ----------------                 -------------------
J. L. Ballesteros           12,400                                  400
H. G. Bernthal              32,804(4)                               400(5)
H. Corless                  34,404(3)(4)                            400(5)
H. M. Dean                  29,654(3)(4)                            400(5)
J. P. Frazee, Jr.           35,038(4)                               400(5)
A. L. Kelly                 27,544(4)                               400(5)
F. A. Krehbiel              36,404(4)                               400(5)
W. A. Pogue                 33,340(3)(4)                            400(5)
J. J. Shea                  21,404(4)                               400(5)

     (1)  Includes  shares  which may be acquired  by exercise of stock  options
pursuant to the Plan.  (2) This does not  constitute a commitment to sell all of
the stated  number of shares.  The amount of shares  offered shall be determined
from  time to time by each  selling  stockholder  in his  sole  discretion.  (3)
Includes beneficial/ownership of shares held indirectly by wife.

     (4)  Includes  stock   compensation   deferred  as  Share  Units  from  the
Non-employee Directors Stock Compensation Plan.
(5) Deferred as Share Units

Additional selling stockholders will be identified by a subsequent appendix.

One or more of the Selling  Stockholders may from time to time make gifts of any
or all of his shares or pledge any or all of his shares as collateral for loans.
In the  event of such gift or of a default  under any such  loan,  the donee may
elect to sell  donated  shares or the  lender may elect to sell  shares  held as
collateral by means of the Prospectus as supplemented.