A nano-sized, TiO2 photocatalytic thin film with a dispersion of anatase crystallites was successfully fabricated from a micron-sized powder by aerosol deposition (AD) at room temperature (RT). Extremely rough, net work-structured, photocatalytic thin films were obtained without any binder or heat treatment. The films were photocatalytically active under both ultraviolet (UV) and solar light as a result of their nano-sized, anatase grains and amorphous phase. Various photocatalytic evaluations confirmed the excellent photocatalytic performance of the AD TiO2 film in terms of organic degradation, pathogen disinfection, and hydrophilicity. This enhanced photocatalytic performance was attributed not only to the nano-crystalline anatase grains, but also to the exceptionally rough, network microstructure and nano-projections capable of supporting the enhanced loading of organic contaminants onto the film surface. Furthermore, because the nano-grained, AD TiO2 photocatalytic thin films were fabricated from low-cost, micron-sized powder with a deposition rate as high as 3 mu m/min at RT, this process promises to be one of the most cost-effective methods for many practical photocatalyst applications. (C) 2008 Elsevier B.V. All rights reserved.