Abstract Diesel particulate filters composed of so-called wall-flow monoliths are well established devices for diesel particulate abatement. Recent improvements in production technology allow implementation of full-featured catalyst functionality in the filter walls. From a reactor engineering point of view such wall-flow reactors with wall-integrated catalyst show fundamental differences compared to conventional flow-through monoliths. The complex interactions of convection, diffusion and reaction in the wall-flow monolith are studied by means of numerical simulation. A two-dimensional model for the flow in one pair of inlet/outlet channels with a generic first order reaction in the catalytic filter wall is developed. Concentration profiles in the reactor and a conventional flow-through catalyst are compared. It is found that in the range of moderate reactor conversion concentration gradients along the inlet channel of the filter are small. Thus the reactor can be described by an approximate one-dimensional model, taking into account only the radial flux through the filter wall and assuming a constant inlet concentration in axial direction along the inlet channel. Light-off curves are computed for the wall-flow and for the conventional flow-through monolith. Significantly better conversion is found for the wall-flow configuration. This can be explained by mass transfer limitation in the conventional flow-through monolith.