Cost-effective catalysts for hydrogen evolution reaction (HER) are attractive for sustainable production of H(2)fuel. Herein, a series of tunable Ni/Fe-Mo carbide catalysts have been synthesized via a sol-gel method coupling with a subsequent high temperature carbonization process. The amount of nickel and iron was tuned in the Mo-7/C precursors, accomplishing a favourable performance of noble-metal-free electrocatalysts for HER. As expected, the designed Ni10Fe4Mo7/C catalyst displays an enhanced catalytic activity toward hydrogen production with an ultralow overpotential (eta(10)= 110 mV) and striking kinetics (eta(onset)= 58 mV, k = 54 mV center dot dec(-1)) in the alkaline electrolyte (1 M KOH), which are comparable to those of the commercial 20% Pt/C catalyst. Such excellent performance of Ni10Fe4Mo7/C could be attributed to the high intrinsic activities of Ni-based alloys (NiMo4) and Mo2C, as well as to the lattice contraction in the Mo2C unit cell, in accordance with its high electrochemical surface area (~133 m(2)center dot g(-1)) and low charge-transfer resistance (~31.5 omega) for the associated electrode.