Cost-effective electrocatalysts for hydrogen evolution reaction are attractive for energy conversion and storage processes. Herein, a variety of molybdenum-based catalysts have been synthesized by means of a simple hydrothermal method using cyclodextrin as structural guiding agent and carbon source. With optimizing the usage of cyclodextrin, both molybdenum oxidate and alpha-type molybdenum carbide can be controllable synthesized in terms of phase composition, morphology and porosity. X-ray diffraction patterns and high resolution transition electronic images show that the as-prepared sample appears a core-shell structure of MoO2/alpha-Mo2C heterojunction. Surprisingly, such heterojunction as an electrocatalyst exhibits a remarkable hydrogen evolution reaction (HER) performance with low overpotential of 100 mV in alkaline electrolyte, and of 152 mV in acidic condition at a current density 10 mA/cm(2), with very low Tafel slope of 50 mV/dec and 65 mV/dec, respectively. This specific activity of presented material is found to be superior to those of the most active Mo-based electrocatalysts reported so far. We believe that our finding of cost-effective electrocatalysts for hydrogen evolution reaction would open the door for future studies and applications of molybdenum compounds. (C) 2017 Elsevier B.V. All rights reserved.