NO adsorption over three types of catalytic systems, such as cation-exchanged zeolites, transition metal oxides supported on gamma-Al2O3, and partially stabilised tetragonal ZrO2 (PSZ) was studied by using the TPD method. NO forms several surface complexes having different desorption temperatures. TPD results compared with catalytic properties of these systems in the selective reduction of NOx by propane under oxygen excess showed that strongly bound nitrites and nitrates appeared to be true intermediates in this reaction.