Ultraviolet (UV) light was introduced into the process of hydrogenation of CO over Ru/TiO2 catalyst which were prepared by a facile impregnation-reduction method. It is found that UV irradiation can promote the conversion of CO into CH4 over Ru/TiO2 at 150-220 degrees C. Based on the testing results of XPS, FT-IR and TPSR for Ru/TiO2 under UV irradiation, it is proposed that the photo-generated electrons induced by the band-gap excitation of TiO2 can transfer to Ru along with the increase of surface electron density of Ru sites. This will further promote the adsorption of CO and its activation at Ru sites, resulting in the photo-enhancement of the methanation of CO. (C) 2013 Elsevier B.V. All rights reserved.