A catalyzed soot filter for a diesel engine comprises a wall flow substrate having a substrate axial length, wherein surfaces of both the internal walls of a plurality of inlet and a plurality of outlet channels comprise a catalytic washcoat of at least one on-wall coating composition for oxidizing NO in exhaust gas to NO2, wherein the washcoat on the inlet channels extends for an axial inlet coating length from an open inlet end to a downstream inlet coating end, the washcoat on the outlet channels extends for an axial outlet coating length from an upstream outlet end to an open outlet end, the axial inlet coating length and the axial outlet coating length are both less than the substrate axial length and the outlet coating length is greater than the inlet coating length.