Crompton Announces Execution of Supplemental Indentures

Crompton Corporation (NYSE:CK) announced today that it
has received the requisite consents to execute a supplemental
indenture amending the indenture governing its 9 7/8% Senior Notes due
2012 (CUSIP Number: 227116AE0) (the "9 7/8% Notes") and a supplemental
indenture amending the indenture governing its Senior Floating Rate
Notes due 2010 (CUSIP Number: 227116AF7) (the "Floating Rate Notes"
and together with the 9 7/8% Notes, the "Notes"). The consents were
obtained pursuant to Crompton's consent solicitation, which commenced
May 16, 2005 (the "Consent Solicitation").
   The supplemental indentures have been executed by Crompton and the
trustee for the Notes, but the amendments therein will not become
operative until such time as the Company notifies Global Bondholder
Services Corporation, the information agent, tabulation agent and
paying agent for the Consent Solicitation, on or prior to September 1,
2005, that each of the conditions set forth in the Company's Consent
Solicitation Statement dated May 16, 2005 (the "Consent Solicitation
Statement"), including the closing of the definitive merger agreement
for an all-stock merger transaction between Crompton and Great Lakes
Chemical Corporation, is satisfied or waived.
   The Consent Solicitation expired at 5:00 p.m., New York City time,
on May 31, 2005. The terms and conditions of the Consent Solicitation
are set forth in the Consent Solicitation Statement.
   Further questions regarding the solicitation may be directed to
the Solicitation Agents, Morgan Stanley & Co. Incorporated at (800)
624-1808 (toll free) or [phone] (collect), and Credit Suisse
First Boston LLC at [phone] (toll free) or [phone]
(collect).
   This announcement is not a solicitation of consents with respect
to any Notes. The solicitation was made solely by the Consent
Solicitation Statement.
   Crompton Corporation, with 2004 sales of $2.5 billion, is a
producer and marketer of specialty chemicals and polymer products.
Additional information concerning Crompton Corporation is available at
www.cromptoncorp.com.

   Forward-Looking Statement

   Certain statements made in this release are forward-looking
statements that involve risks and uncertainties, including, but not
limited to, statements about the benefits of the business combination
of Crompton and Great Lakes, including future financial and operating
results, the combined companies' plans, objectives, expectations and
intentions, general economic conditions, the outcome and timing of
antitrust investigations and related civil lawsuits to which Crompton
is subject, the ability to obtain selling price increases, pension and
other post-retirement benefit plan assumptions, energy and raw
material prices and availability, production capacity, changes in
interest rates and foreign currency exchange rates, changes in
technology, market demand and customer requirements, the enactment of
more stringent environmental laws and regulations, the ability to
realize expected cost savings under Crompton's cost reduction
initiatives, the amount of any additional earn-out payments from GE,
the ability to reduce Crompton's debt levels, and other risks and
uncertainties detailed in Crompton's filings with the Securities and
Exchange Commission. These statements are based on Crompton's
estimates and assumptions and on currently available information. The
forward-looking statements include information concerning our possible
or assumed future results of operations, and Crompton's actual results
may differ significantly from the results discussed. Forward-looking
information is intended to reflect opinions as of the date this
release was issued and such information will not necessarily be
updated by Crompton.