debenture

News Release

Chromos Makes Payment on Debenture

For Immediate Release: August 2, 2005

Burnaby, British Columbia, Canada: Chromos Molecular Systems Inc. ("Chromos"; TSX: CHR) announced that it issued 1,294,526 common shares in payment of interest and $1,500,000 of the principal amount owing for the convertible debenture issued to CellExSys Inc. (“CellExSys”) shareholders during the 2004 acquisition of CellExSys.

The original principal amount of the convertible debenture was $3,375,000. The remaining principal is convertible into Chromos shares at the option of Chromos and bears interest at 2% per annum and must be repaid on or before July 27, 2006.

About Chromos

Chromos is a cellular engineering and therapeutics company creating value through engineering production quality cell lines for the manufacture of biopharmaceuticals, and the development of innovative biological therapies for debilitating diseases. Chromos is achieving these objectives with its ACE System (Artificial Chromosome Expression) and REM (Rapid Expansion Method) technologies. In the near term, Chromos will focus on continued commercialization of the ACE System for engineering cell lines. To date Chromos has entered into corporate partnerships related to cell line engineering with partners including Pfizer Inc., Centocor, Inc. and Cambridge Antibody Technology. In addition, the Company has a strategic alliance with AppTec to provide customers with a complete range of cell line development and manufacturing services.

Risks and Uncertainties

Certain of the statements contained in this press release are forward-looking statements which involve known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of Chromos (the “Company”), or industry results, to be materially different from any future results, performance or achievements expressed or implied by such forward-looking statements.

To the extent possible, management implements strategies to reduce or mitigate the risks and uncertainties associated with the Company’s operations. Operating risks include (i) the continued availability of capital to finance the Company’s activities; (ii) the Company’s limited cash position, (iii) the ability to successfully obtain proof of the effectiveness of the Company’s technology (iv) the ability to complete and maintain corporate alliances relating to the development and commercialization of the Company’s technology; (v) the ability to obtain and enforce patent and other intellectual property protection for the Company’s technology; (vi) market acceptance of the Company’s technology; (vii) the competitive environment and impact of technological change; (viii) the Company’s ability to attract and retain employees to carry out its business plans and (ix) the timely development and commercialization of any technology or products that are contingent on the completion and maintenance of corporate alliances with third parties. Further details on Chromos’ operating risks can be found in the Company’s Quarterly and Annual Reports to Shareholders.

FOR FURTHER INFORMATION:

Kathryn Hayashi, CA

Vice President Finance

Tel: 604-415-7132

Email: khayashi@chromos.com