1. Name and Address of Reporting Person
   Gum, Mary
   199 Benson Road
   Middlebury, CT 06749
   USA
2. Issuer Name and Ticker or Trading Symbol
   Crompton Corporation
3. IRS or Social Security Number of Reporting Person (Voluntary)
4. Statement for Month/Day/Year
   01/21/2003
5. If Amendment, Date of Original (Month/Day/Year)
6. Relationship of Reporting Person(s) to Issuer (Check all applicable)
   ( ) Director                   ( ) 10% Owner
   (X) Officer (give title below) ( ) Other (specify below)
   Executive V.P. - OSI
7. Individual or Joint/Group Filing (Check Applicable Line)
   (X) Form filed by One Reporting Person
   ( ) Form filed by More than One Reporting Person

TABLE I -- Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

+------------------------------+----------+----------+---------+--------------------------+--------------+-----------+------------+
|1. Title of Security          |2. Trans- |2A.Execu- |3. Trans-|4. Securities Acquired (A)|5. Amount of  |6. Owner-  |7. Nature   |
|                              |   action |   action |   action|   or Disposed of (D)     |Securities    |   ship    |   of In-   |
|                              |   Date   |   Date   |   Code  |                          |Beneficially  |   Form:   |   direct   |
|                              |          |          |         |                          |Owned         |   Direct  |   Bene-    |
|                              |  (Month/ |  (Month/ |         |                          |Following     |   (D) or  |   ficial   |
|                              |   Day/   |   Day/   +-----+---+-----------+---+----------+Reported      |   Indirect|   Owner-   |
|                              |   Year)  |   Year)  |Code |V  |Amount     |A/D|Price     |Transaction(s)|   (I)     |   ship     |
+------------------------------+----------+----------+-----+---+-----------+---+----------+--------------+-----------+------------+
                                                                                        
Common Stock                                                                               34340          D





TABLE II -- Derivative Securities Acquired, Disposed of, or Beneficially Owned

+----------+--------+-------+-------+---------+-----------+---------------------+----------------+----------+-------+-------+------+
|1.        |2.      |3.     |3A.    |4.       |5.         |6.                   |7.              |8.        |9.     |10.    |11.   |
|          |        |       |       |         |           |                     |                |          |Number |Owner- |      |
|          |        |       |       |         |           |                     |                |          |of     |ship   |      |
|          |        |       |       |         |           |                     |                |          |Deriv- |Form of|      |
|          |        |       |       |         |           |                     |Title and Amount|          |ative  |Deriv- |      |
|          |        |       |       |         |           |                     |of Underlying   |          |Secur- |ative  |Nature|
|          |Conver- |Trans- |Execu- |         |Number of  |                     |Securities      |          |ities  |Secur- |of    |
|          |sion or |action |tion   |         |Derivative |Date Exercisable     +-------+--------+          |Benefi-|ity:   |In-   |
|          |Exercise|Date   |Date   |         |Securities |and Expiration Date  |       |Amount  |          |cially |Direct |direct|
|          |Price of|       |       |Transac- |Acquired(A)|(Month/Day/Year)     |       |or      |          |Owned  |(D) or |Bene- |
|Title of  |Deriv-  |(Month/|(Month/|tion Code|Disposed(D)+----------+----------+       |Number  |Price of  |       |In-    |ficial|
|Derivative|ative   | Day/  | Day/  +------+--+-----+-----+Date Exer-|Expira-   |       |of      |Derivative|       |direct |Owner-|
|Security  |Security|Year)  |Year)  |Code  |V |(A)  |(D)  |cisable   |tion Date |Title  |Shares  |Security  |       |(I)    |ship  |
+----------+--------+-------+-------+------+--+-----+-----+----------+----------+-------+--------+----------+-------+-------+------+
                                                                                
NQ Stock    $6.38    01/21/2         A     43654       01/21/2004 02/20/2013 Common  43654    $0.0000    43654   D
Option               003                                                         Stock
(Right to
Buy)
NQ Stock    $7.25                                                     11/21/2012 Common                      21207   D
Option                                                                           Stock
(Right to
Buy)
NQ Stock    $7.92                                                     11/22/2011 Common                      47374   D
Option                                                                           Stock
(Right to
Buy)
NQ Stock    $8.1562                                                   11/30/2010 Common                      75000   D
Option                                                                           Stock
(Right to
Buy)
NQ Stock    $8.343                                                    11/19/2009 Common                      164045  D
Option                                                                           Stock
(Right to
Buy)
ISO Stock   $6.38    01/21/2         A     31346       01/21/2005 01/21/2013 Common  31346    $0.0000    31346   D
Option               003                                                         Stock
(Right to
Buy)
ISO Stock   $7.25                                                     10/22/2012 Common                      13793   D
Option                                                                           Stock
(Right to
Buy)
ISO Stock   $7.92                                                     10/23/2011 Common                      12626   D
Option                                                                           Stock
(Right to
Buy)
ISO Stock   $8.3437                                                   10/19/2009 Common                      35955   D
Option                                                                           Stock
(Right to
Buy)

Explanation of Responses:


Options will vest as follows:  25,000 on 1/21/2004, 9,327 on 1/21/2005 and 9,327
on 1/21/2006.

Options will vest as follows:  15,673 on 1/21/2005 and 15,673 on 1/21/2006.



SIGNATURE OF REPORTING PERSON
/s/ Mary Gum

DATE
01/23/2003