A facile sulfurization process has been utilized to synthesize WS2/WO3 heterostructure using WO3 square nanosheets as support. The thin WO3 nanosheets synthesized by hydrothermal method may provide large surface area with homogeneous dispersion, which is favorable for exposing active sites and fast charge transfer for hydrogen evolution reaction (HER). SEM and TEM images show that the thin square nanosheets of as-prepared WS2/WO3 heterostructure are well kept after sulfurization process. The formation of WS2 on the surface of heterostructured nanosheets may greatly enhance the intrinsic HER activity and conductivity. The electrochemical measurements demonstrate the obviously enhanced HER activity of WS2/WO3 heterostructured nanosheets compared with pure WO3 or bulk WS2, illustrating that the synergistic effect derived from heterostructured WS2/WO3 may be a key to enhance HER performances of WO3. Therefore, designing heterostructure of transition metal sulfides/oxides may be a promising strategy to prepare efficient electrocatalysts for HER. (C) 2017 Elsevier B.V. All rights reserved.