A novel CuS-ZnS1-xOx/g-C3N4 nanocomposites were prepared by a thermal decomposition process and a hydrothermal method. The effects of the Cu(NO3)(2) dopant precursor concentration and weight ratio of g-C3N4/ZnS1-xOx on the morphology, crystalline properties, optical property, photocurrent were investigated by using the field-emission scanning electron microscope (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectra (DRS), photocurrent response, and hydrogen production tests. Decorating CuS improved the absorption of the heterostructured photocatalysts. H-2 production rate was increased from 9200 to 10,900 mu mol h(-1) g(-1) by incorporating CuS. By loading 5 wt% g-C3N4 on CuS- ZnS1-xOx, the maximal hydrogen production rate of the composite catalyst reached 12,200 mu mol g(-1)h(-1) under UV light irradiation. Introducing g-C3N4 helps to separate photogenerated electron-hole pairs. After being operated for 3 cycles, the recycled CuS ZnS(1-x)O(x)g-C3N4 photocatalyst retained 87% of its original activity. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.