CuWO4 films with feature particle sizes of 100-200nm and thickness up to 700-900 nm on fluorine-doped tin oxide (FTO) substrates were prepared by hydrothermal synthesis. The prepared CuWO4 films were treated in hydrogen atmosphere at constant temperature 300 degrees C for different annealing time and used for photoelectrochemical (PEC) water oxidation. Compared with pristine CuWO4 film, the optimized hydrogen-treated CuWO4 film presented three times enhanced photocurrent density of 0.75 mA/cm(2) at 1.2V vs. Ag/AgCl in 0.1 M Na2SO4 solution under the illumination. The donor density of hydrogenated CuWO4 film determined by Mott-Schottky analysis was improved one order of magnitude as well. The enhanced photoelectrochemical activity could be attributed to the formation of oxygen vacancies after hydrogen treatment, which facilitated the charge transport and collection. (C) 2015 Elsevier B.V. All rights reserved.