The reaction of 2-pyridylamino-N,N-bis(2-methylene-4-ethyl-6-tert-butylphenol) (H2L) and MoCl5 gives a molybdenum(VI) complex [MoL(O)(2)] 1, a new molecular electrocatalyst, which has been determined by X-ray crystallography. Electrochemical studies show that complex 1 can catalyze hydrogen evolution from acetic acid or aqueous buffer. Turnover frequency (TOF) reaches a maximum of 68 (in N,N-Dimethylformamide (DMF)) and 356 (in buffer, pH 6.0) moles of hydrogen per mole of catalyst per hour, respectively. Sustained proton reduction catalysis occurs at glassy carbon (GC) electrode to give H-2 over a 69 h electrolysis period and no observable decomposition of the catalyst. (C) 2014 Elsevier Ltd. All rights reserved.