Photoassisted conductive atomic force microscopy had been used to study the topography and the electrons transport properties of WO3 TiO2 and composite WO3/TiO2 nano-thin films prepared by sol-gel method on substrate of ITO glass. The results indicated that the composite WO3/TiO2 had a very large opening voltage gap in dark compared with pure WO3 or TiO2, while remarkable ohmic character under UV light resulting from the effective separation of photogenerated electrons and holes at the WO3 and TiO2 interface could be detected. This implied that the composite films of WO3/TiO2 had an outstanding photo-electric switching effect. (c) 2005 Elsevier B.V. All rights reserved.