Photocatalytic water treatment over bare WO3 under visible light irradiation combined with ozonation (O-3/vis/WO3) was investigated using an aqueous phenol solution as model wastewater. The O-3/vis/WO3 treatment exhibited a much higher total organic carbon removal than ozonation alone. Bare WO3 was found to function as an active visible-light-responsive photocatalyst for decomposition of organic compounds in the presence of ozone, which readily reacts with photoexcited electrons in the conduction band of WO3. (C) 2010 Elsevier B.V. All rights reserved.