Kinetics and mechanism of NO and oxygen coadsorption on TiO2 at room temperature, which is the key step of the catalytic removal of NOx pollutants from air, were studied. NO adsorption on TiO2 in the absence of oxygen is weak and reversible, but it is found to strongly increase in the presence of oxygen. The ratio between the amount of adsorbed NO and O2 in the course of adsorption is constant and close to three. A FTIR spectroscopic study reveals that the amount and composition of N-containing species on the TiO2 surface strongly depend on the contact time with the initial NO−O2 mixture and on its composition. At relatively small exposures, IR bands assigned to NO− and nitrosyl complexes Tin+−NO (n = 3−4) are predominant in the spectra. With increasing contact time, NO− disappears, and IR bands of NO3− and possibly NO2− appear and grow. IR spectra observed upon NO2 adsorption are similar to those after exposure to NO−O2 mixtures. Exposure of the sample with preadsorbed 14NO2 to gaseous 15NO results in a cha