Ternary Zn1-xCuxO nanorods with a controllable optical band gap were fabricated by a simple electrochemical route. XRD confirmed that crystalline nanorods with copper concentrations from 1% to 10% had a hexagonal wurtzite structure. The incorporation of copper in the ZnO matrix, the amount of which was determined using XPS, red-shifted the absorption edge of the Zn1-xCuxO nanorods to an extent that was proportional to the copper content. Photoelectrochemical (PEC) measurements clearly revealed that the Zn1-xCuxO nanorods increased the photocoversion efficiency to 2 times that of pure ZnO, and they exhibited a greater photoresponse to visible light because of the band gap narrowing effect. Hence, the Zn1-xCuxO with narrowing band gap illustrated great potential for large light-harvesting device. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.