An oxygen-vacancy rich, bismuth oxide (Bi2O3) based MoS2/Bi2O3 Z-scheme heterojunction catalyst (2-BO-MS) was prepared in an autoclave hydrothermal method using ethanol and water. The performance of MoS2/Bi2O3 catalyst was examined for photocatalytic hydrogen evolution, photoelectrochemical activity, and crystal violet (CV) dye degradation by comparing with pristine Bi2O3 and MoS2. The hydrogen evolution performances of 2-BO-MS catalyst exhibited 3075.21 mu mol g(-1)h(-1), which is 7.18 times higher than that of MoS2 (428.14 mu mol g(-1)h(-1). The XPS, XRD and HRTEM analyses covered that the superior photocatalytic performance of 2-BO-MS catalyst might have stemmed out due to the existence of oxygen vacancies, enhanced strong interfacial interaction between MoS2 and Bi2O3 and specific surface area. The in-depth investigation has been performed for MoS2/Bi2O3 Z-scheme heterojunction using several characterization techniques. Moreover, the photocatalytic mechanism for hydrogen evolution and photodegradation were proposed based on trapping experiment results. This results acquired using MoS2/Bi2O3 Z-scheme heterojunction would be stepping stone for developing heterojunction catalyst towards attaining outstanding photocatalytic activity. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.