CoMoS phase with metallic character plays crucial role on enhancing the activity of MoS2 electrocatalysts for hydrogen evolution reaction (HER). However, only Co atoms located in the edges of MoS2 can create CoMoS phase, so it is a challenge to obtain CoMoS phase with homogeneous distribution limited by the layered MoS2 and doping method of Co. Herein, we reported a simple one-pot hydrothermal method to prepare novel ternary CoS2/MoS2/RGO with CoMoS phase for HER using reduced graphene oxide (RGO) as support. XPS proves the formation of CoMoS phase, implying the enhanced activity for HER. RGO support ensures the well distribution of CoMoS phase and enhances the conductivity of CoS2/MoS2/RGO. Compared to CoS2/RGO, MoS2/RGO and CoS2/MoS2, the obtained CoS2/MoS2/RGO shows superior activity for HER with an onset overpotential of -80 mV (vs. RHE), small Tafel slope of 56 mV dec(-1), high exchange current density of 11.4 mu A cm(-2) and rigid electrochemical durability. The enhanced performances for HER may be ascribed to the formation of CoMoS phase with high activity and the existence of RGO support with good electrical conductivitys in ternary CoS2/MoS2/RGO. Therefore, the introduction of CoMoS phase and RGO into MoS2 could effectively enhance electrocatalytic properties for HER. (C) 2017 Elsevier B.V. All rights reserved.