Photocatalytic titanium oxide (TiO2) films were prepared by plasma-enhanced chemical vapor deposition (PECVD). All the films prepared in this study were nearly stoichiometric titanium dioxide. X-ray diffraction shows weak diffraction peaks of anatase even in the as grown film, and their intensities increase after 600 degrees C annealing. The crystalline phase changes from anatase to rutile after 900 degrees C annealing. The anatase films have a surface where high-density small grains have gathered, while the rutile film has an uneven surface with elongated gains. When the PECVD-TiO2 films were irradiated by UV-light, the photocatalytic reactions occur on the film surface, namely the photoinduced decomposition of organic compounds and the photo-induced hydrophilicity. These photocatalytic reactions occur more strongly on the anatase film than the rutile film. Moreover, photocatalytic activity strengthens with increasing crystallinity of anatase. (c) 2005 Elsevier B.V. All rights reserved.