The generation of hydrogen (H-2) through photocatalytic water splitting with the employment of various co-catalysts has attracted much attention. In this study, the CoP was successfully decorated on Zn0.5Cd0.5S as a highly efficient co-catalyst via a two-step in-situ chemical deposition method. The chemical as well as photophysical properties of the as-obtained CoP/Zn0.5Cd0.5S samples were characterized by X-ray diffractometry (XRD), Transmission electron microscope (TEM), UV-vis diffusion reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and surface photovoltage spectroscopy (SPV). The CoP/Zn0.5Cd0.5S composite sample with 5% molar content showed the highest photo catalytic H-2 evolution activity with a corresponding H-2 evolution rate of 734 umol h(-1), which was about 20 times higher than that of pure Zn0.5Cd0.5S sample and 2 times higher than Pt loaded Zn0.5Cd0.5S sample under visible light irradiation. The photocatalytic activity of the CoP/Zn0.5Cd0.5S composite sample was stable even after 4 cycling photocatalytic experiments. A possible mechanism on the photocatalytic enhancement of CoP was systematically investigated, which can provide a novel concept for the synthesis of other desirable photocatalytic materials with high photocatalytic performance. (C) 2017 Elsevier B.V. All rights reserved.