A (oxy)nitride composite- InN/GaZnON- is synthesized and utilized as the photocatalyst for visible-light-driven overall water splitting. The effect of Ni doping on the performance of the composite photocatalyst is investigated. The X-ray diffraction pattern indicates that the catalyst is a composite material consisting of InN and GaZnON phases. Ni is doped into the crystal lattices of the two phases. Ni doped InN/GaZnON composite achieves overall water splitting even without the loading of an additional cocatalyst. The doping of Ni greatly improves the visible light absorption and the water splitting activity. With the optimum elemental mole ratio, In/Ga/Zn/Ni = 1/1/1/0.05, H-2 and O-2 evolution rates achieve 2.23 and 1.15 mu mol h(-1), respectively. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.