The combined entity of Clean Diesel Technologies (CDTI) and Catalytic Solutions, Inc. (CSI) is a vertically integrated global manufacturer and distributor of emissions control systems and products. It is focused on the heavy duty diesel and light duty vehicle markets. CSI invented Mixed Phase Catalyst technology, a fundamentally unique and patented materials technology for the development of catalysts for emissions control and chemical processes. 

CDTI and CSI merged in December 2010.