In this paper, silver-loaded TiO 2 photocatalyst was prepared by photochemical impregnation method and characterized by transmission electron microscopy (TEM), diffuse reflectance spectra (DRS), photooxidation of phenol and photoreduction of Cr(VI). Electron paramagnetic resonance (EPR) was used to detect photoproduced paramagnetic radicals. The correlation of photocatalytic activity and photogenerated reactive species was discussed, and the mechanism of silver-loaded TiO 2 for enhancement of photocatalytic activity was elucidated. The results show that deposited silver on TiO 2 surface acts as a site where electrons accumulate. The better separation between electrons and holes on the modified TiO 2 surface allowed more efficiency for the oxidation and reduction reactions. The enhanced photocatalytic activity was mainly attributed to the increased amounts of O 2 − reactive species and surface Ti 3+ reactive center on silver-loaded TiO 2 photocatalyst.