CuS/ZnS composite particles with diameter of 200-400 nm were successfully prepared by a simple cation-exchange reaction using ZnS spheres as a precursor. CuS nanoparticles with a few nanometers in diameter were observed on the surface of composite particles. The synthesized CuS/ZnS composite particles showed photocatalytic property effective for H-2 evolution from an aqueous Na2S and Na2SO3 solution under visible light irradiation without any cocatalysts. The rate of H-2 generation was found to be strongly dependent on the CuS content. The highest rate of H-2 evolution reached 695.7 mu mol h(-1) g(-1), which was almost 7 times as high as that of the mechanical mixture of CuS and ZnS. The enhancement in the photocatalytic activity of CuS/ZnS composite particles is supposed to be due to the direct interfacial charge transfer of the CuS/ZnS heterojunction. (C) 2015 Elsevier Ltd. All rights reserved.