The exhaust gas aftertreatment systems in automotive applications have become quite complex and expensive, due to progressively tighter emission limits for CO, hydrocarbons (HC), NOx and particulate matter (PM).For example, typical configuration for Diesel engines include an oxidation catalyst for abatement of CO and HC, deNOx catalyst, filter and often also ammonia slip catalyst [1].Therefore, a large effort has been directed to optimization of catalytic coatings and also in possible combination of different functions in a single monolith, e.g., by using coated filter or multiple catalytic layers.The effective diffusivity in the coated layer(s) is one of key properties that determine utilization of the active catalytic material and overall performance of the device.