In this investigation, transparent TiO2 films were deposited with various direct current powers, ranging from 200 W to 500 W by facing target reactive Sputtering technique to study the photocatalytic activity by the measurement of photo-decomposition of methanol under UV-visible irradiation. All the as-deposited TiO2 thin films, prepared with sputtering power over 200 W, show crystalline structure of anatase phase. The crystallinity of the TiO2 thin films improves greatly with the increase of sputtering power. The photo-decomposition efficiency of TiO2 film increases monotonically with the applied power. An explanation is proposed for the variation of photocatalytic activity with varying Sputtering power based on the surface morphology and crystallinity of the TiO2 thin films. (C) 2008 Elsevier B.V All rights reserved.