We have investigated the photoactivated O2 adsorption/desorption, the isotope equilibration (POIEq) and the isotope exchange (POIEx) in the O2–(TiO2–x/TiO2) (Degussa P-25) system, as well as the adsorption and POIEx in the NO–(TiO2–x/TiO2) systems. The photoactivation spectra of the hole centers generation, of POIEq and of the NO photo-adsorption were measured in 300-500 nm range using a continuously adjustable wavelength light source. The spectral characteristics of the NO photoadsorption are close to those of POIEq. Both electron-donor and hole centers are manifested in these processes. For O2 photodesorption, CO oxidation, POIEx and POIEq the hole centers are responsible. In case of O2 and NO photoadsorption both types of centers are active. The maxima of POIEq and of NO photo-adsorption are placed near 420 nm beyond the edge of TiO2 bandgap absorption. It was found that the N18O - Ti16O2 exchange occurs not only under the illumination, but it can be activated by a preliminary sample illumination in vacuum