It is shown for the first time that the photoassisted reduction of NO by CO into N2 and N2O can occur on TiO2 catalysts upon visible light irradiation (λ > 380 nm) at room temperature. The selectivity of photoreduction of NO into N2 reaches 90−95%. The CO2 formed which predominantly remains on the surface can be quantitatively desorbed after completion of the photoreaction by heating TiO2 to ∼500 K. The rates of NO consumption and product accumulation remain virtually constant upon successive admissions of the CO−NO mixture thus indicating a high stability of catalyst activity. It is found that the quantum yield of NO photoreduction by CO is considerably greater for visible light irradiation (λ = 405 + 436 nm) than for UV irradiation (λ = 365 nm). Experiments with 18O-enriched NO revealed that, under visible light irradiation, an intense oxygen isotopic exchange between NO and TiO2 develops. The photocatalytic reaction requires the presence in nonstoichiometric TiO2- x of electron-donor centers (Ti3+ ions, F and F+ centers) able to absorb visible light. A reaction mechanism is proposed which includes the following stages:  (a) NO photoadsorption along two parallel routes, by e- capture from the electron-donor center by NO to yield adsorbed NO- species and by NO interaction with the hole O- to give adsorbed nitrite NO2 -; (b) reduction of NO- into N2O and further into N2; and (c) photoreduction of adsorbed nitrite NO2 - into N2O and further into N2 by CO which regenerates the donor centers. It is assumed that the photoinduced oxygen heteroexchange proceeds via adsorbed nitrite complexes.