A catalytic deSoot-deNOx system, comprising Pt and Ce fuel additives, a Pt impregnated wall-flow monolith soot filter and a vanadia-type monolithic NH3 - SCR catalyst, was tested with a 2 cylinder DI diesel engine. The soot removal efficiency of the filter was 98-99% (mass), the balance temperature (stationary pressure drop) was 315 °C at an engine load of 55%. The NOx-emission at high loads is around 15% lower than those of engine running without fuel additives. The NOx conversion ranged from 40 to 73%, at a NH3/NOx ratio of 0.9, both measured at a GHSV of 52,000 l/l/h. The maximum NOx conversion was obtained at 400 °C. No deactivation was observed after 380 h time on stream.