The design of p-n heterojunction photocatalysts to overcome the drawbacks of low photocatalytic activity that results from the recombination of charge carriers and narrow photo-response range is promising technique for future energy. Here, we demonstrate the facile hydrothermal synthesis for the preparation of Bi2O3/MoS2 p-n heterojunction photocatalysts with tunable loading amount of Bi2O3 (0-15 wt%). The structure, surface morphology, composition and optical properties of heterostructures were studied using X- ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-visible absorption spectroscopy, Brunauer-Emmett-Teller (BET) surface area, photoluminescence (PL), electrochemical impedance spectroscopy (EIS). Compare to pure Bi2O3 and MoS2, the Bi2O3/MoS2 heterostructures displayed significantly superior performance for photocatalytic hydrogen (H-2) production using visible photo-irradiation. The maximum performance for hydrogen evolution was achieved over Bi2O3/MoS2 photocatalyst (10 mu mol h(-1) g(-1)) with Bi2O3 content of 11 wt%, which was approximately ten times higher than pure Bi2O3 (1.1 mu mol h(-1) g(-1)) and MoS2 (1.2 mu mol h(-1) g(-1)) photocatalyst. The superior performance was attributed to the robust light harvesting ability, enhanced charge carrier separation via gradual charge transferred pathway. Moreover, the increased efficiency of Bi2O3/MoS2 heterostructure photocatalyst is discussed through proposed mechanism based on observed performance, band gap and band position calculations, PL and EIS data. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.