Cu2O/TiO2 nanoparticles were prepared by solvothermal method, which formed the heterostructure of Cu2O/TiO2. Due to the heterostructure, the H-2 evolution rate under simulated solar irradiation was increasingly promoted. Meanwhile a certain amount of Cu particles which were confirmed by Transmission Electro Microscopy (TEM) and X-Ray Photoelectron Spectroscopy (XPS), formed on the surface of Cu2O/TiO2, and the photoactivity was accordingly further enhanced. The stabilized activity was maintained after many times irradiation. It is interesting that after a few hours irradiation the amount of Cu particles on the surface kept unchanged in the presence of Cu2O and TiO2. The Cu particles that formed during hydrogen generation reaction play a key role in the further enhancement of the hydrogen production activity. In this study, it is the first time to study the details on the formation of the stable ternary structure under simulated solar irradiation and their synergistic effect on the photoactivity of the water splitting. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.