In this work, a series of metallic cobalt-molybdenum carbide@graphitic carbon (CoMo(x:y)-T@GC) nanocomposites for the electrochemical hydrogen evolution reaction (HER) were synthesized by a sol-gel method. In the as-prepared nanocomposites, beta-Mo2C and metallic Co coexisted and were encapsulated by graphitic carbon. The presence of metallic Co effectively enhanced the crystallinity of beta-Mo2C, charge transfer efficiency and electrochemical active surface area (ECSA), thus resulting in the improved HER catalytic activities of the CoMo(x:y)-T@GC nanocomposites. The optimized electrocatalyst CoMo(0.5:0.5)-800@GC required the lowest overpotential of similar to 165 mV to deliver a current density of 10 mA cm(-2) in 0.1 M KOH, which was at the forefront compared with recently reported Mo2C-based electrocatalysts. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.