Several promising catalysts for the selective reduction of NOx with organic compounds were made into large scale samples (cylindrical, phi = 118 mm, length = 50 mm), either as washcoated honeycomb monoliths (400 cell/in(2)) or as packings of pellets with a diameter of 2-3 mm. These samples were tested under diesel exhaust gas conditions with the SV = 16 400 h(-1), in the temperature range from 200 to 460 degrees C. When propylene was used as a reducing agent, Pt/Al2O3, Pt-ZSM-5 and Au/Al2O3 + Mn2O3 showed high catalytic activities in the low temperature range from 200 to 250 degrees C. Cu-ZSM-5 (propylene as a reductant), Co/Al2O3 (methanol) and Ag/Al2O3 (ethanol) showed high activities at temperatures >350 degrees C. Except for the manifestation of differences in the activity among catalysts, the general behaviors of these catalysts, such as the active temperature range, selectivity to N2O and emission of non-reacted or incompletely oxidized reductants, were similar to that shown when model gas mixture systems were used.