The applicability of thermal anemometry with constant wire temperature for characterization of the flow distribution in microchannel reactors was first proven by a comparison. of simulation and experimental results using uncoated microchannels. The anemometry was then applied for structured reactor foils with different nanoparticle washcoats. Homogeneity of the coatings observed by scanning electron microscopy showed good correlation to the results of the anemometry. (C) 2004 American Institute of Chemical Engineers.