For the first time, the nanocrystalline Co0.85Se (NC-Co0.85Se) electrocatalyst with high efficiency of hydrogen evolution reaction (HER) has been synthesized through a facile DMF-solvothermal reaction. Compared to hydrothermally synthesized Co0.85Se (H-Co0.85Se) with relatively poor HER performance, the NC-Co0.85Se catalyst exhibits superior HER performances. Electrochemical measurements show that the NC-Co0.85Se has a very low onset overpotential of similar to 127 mV in 0.5 M H2SO4, a high cathode current density of 30 mA cm(-2) at similar to-210 mV vs RHE, and excellent long-term stability. Most importantly, the NC-Co0.85Se exhibits an ultra-small Tafel slope of 34.1 mV dec(-1), which is close to that of noble platinum (Pt) catalyst (30.1 mV dec(-1)). It is promising for NC-Co0.85Se as a highly efficient non-noble-metal electrocatalyst to replace precious Pt-based catalysts for hydrogen evolution. (C) 2017 Elsevier Ltd. All rights reserved.