The zirconium dioxide surface has a wide variety of adsorption sites differing in their nature. The proportions of these sites can be changed by varying the oxide preparation and pretreatment conditions. This fact shows itself as a wide diversity of surface structures resulting from NO and O2 adsorption. Under conditions of the selective catalytic reduction of NOx, the most stable nitrogen oxide species are nitrates that result from the interaction between NOx and the ZrO2 surface. The concentrations of the other nitrogen-oxygen surface compounds are two orders of magnitude lower. The routes of NO3- formation and decomposition on the ZrO2 surface are discussed. In these routes, monodentate nitrates (which show themselves at 1550-1555 cm-1) are considered as intermediates in the formation and decomposition of bidentate NO3-.