Decreasing the level of NOx and particulate matter simultaneously from the exhaust of diesel engines has been demonstrated using newly developed catalyst compositions. Ignition temperatures below 400°C were observed in laboratory tests using catalyzed diesel particulate traps mounted to a single cylinder diesel engine connected to a dynamometer. This paper will report on the initial laboratory studies undertaken to evaluate the fundamental interaction between NOx and benzene derived particulate over customized catalytic materials. It will also address the role such particulates have on NOx reduction and discuss the effectiveness of decreasing NOx and particulates simultaneously on catalytically activated diesel particulate traps. Current and future work being performed on heavy duty truck engines incorporating these new catalyst compositions on a membrane-containing ceramic foam material is also addressed.