The effect of soot on the ammonia adsorption and the catalytic properties of a diesel particulate filter coated with a catalyst for the selective catalytic reduction of NO with ammonia (SDPF) was studied by means of model-gas experiments. After loading of the SDPF with model soot from 0 to 10 g I-1, the NH3 storage as well as the catalytic DeNO(x), behavior in the standard SCR reaction was studied at temperatures between 423 and 673 K for a gas hourly space velocity of 40.000 h(-1). In the presence of soot, less NH3 is adsorbed as shown by a breakthrough which occurs at earlier times-on-stream than in the absence of soot. Furthermore, the NO conversion on a soot-loaded SDPF is lower by up to 20% with respect to a soot-free SDPF. A 1-D microscopic filter wall model is presented. It contains the soot distribution along the filter wall, a kinetic SCR model and diffusive mass transfer of species through the wall-trapped soot. The soot inside the porous wall close to the zeolitic washcoat acts as a diffusive barrier, i.e., mass transfer through the soot is the rate-limiting process for the SCR reaction under the conditions studied. The model is also able to explain the NH3 storage behavior as well as the decrease of NO conversion in the standard SCR reaction for soot-free and soot-loaded SDPF. Also, a soot distribution with a high soot-coverage of the porous filter wall close to the inlet channel, a slightly covered middle part and a soot-free zone close to the outlet was derived from the model. (C) 2017 Elsevier Ltd. All rights reserved.