Up to now, it is still a great challenge to develop active, durable and low-cost non-precious metal catalysts toward hydrogen evolution reaction (HER). In this paper, we synthesized ultrafine Co6Mo6C nanocrystals on reduced graphene oxide (RGO) support (Co6Mo6C/RGO). The Co6Mo6C/RGO shows Pt-like HER performance, which exhibits almost zero onset overpotential, and very small overpotential of 64 mV at 10 mA cm(-2). In addition, the Co6Mo6C/RGO has a very small Tafel slope of 44 mV dec(-1) and a high exchange current density of 0.402 mA cm(-2), suggesting fast reaction kinetics. Furthermore, the Co6Mo6C/RGO demonstrates superior durability in acid electrolyte. The distinguished HER performance makes Co6Mo6C/RGO the promising candidate as non-precious metal catalyst for HER in acid electrolyte. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.