A mesoporous TiO2/WO3 nanohoneycomb at a molar ratio of 3:1 was prepared by sol-gel method for photoelectrochemical splitting of water. In order to create a highly porous structure, the composite TiO2/WO3 with a block copolymer internal template was deposited on the substrate covered with polystyrene (PS) nanospheres. A mesoporous TiO2/WO3 composite nanohoneycomb was obtained after removing the PS spheres and copolymer by thermal treatment. It exhibited a lower band gap energy than TiO2 so that the optical absorption edge was shifted toward the visible light region. It also showed a better photoelectrochemical efficiency of water splitting and higher production of hydrogen due to lower energy gap, higher reactive surface area, and better charge separation efficiency. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.