In this work, the Cu (0.1, 0.5, 1.0, and 5.0 mol.-%)-incorporated ZnO nanoparticles (CuxZnyO) are prepared by a conventional hydrothermal method. Powder X-ray diffraction patterns confirm that Cu ion is stably inserted into the framework of ZnO, and the crystallite size decreases as the amount of Cu ion increases. With the insertion of Cu ions into ZnO, the recombination rate of photogenerated charge carriers is found to be low which in turn increases the photocatalytic activity. The H-2 production activity of Cu-inserted ZnO catalysts is higher than the pure ZnO catalyst. Among the different samples, the Cu0.01Zn0.99O catalyst having a 1.0 mol.-% of Cu shows the higher H-2 production activity. The enahanced H-2 production activity of CuxZnyO catalysts is attributed to the longer life-time of excited electrons during the photo catalytic reaction and the decreased electron-hole recombination rate. (C) 2017 Elsevier B.V. All rights reserved.