The effects of cobalt ion on the hydrogen evolution reaction (HER) in sulfate solution were studied by several electrochemical measurements, such as linear sweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry. The charge transfer resistance and the apparent activation energy can be decreased with the cobalt ion adding into the sulfate solution. The calculated values of apparent activation energy are 43.4 kJ mol(-1) and 31.9 kJ mol(-1) for HER in the MnSO4-(NH4)(2)SO4 solution without and with cobalt ion respectively. At the same temperature, the charge transfer resistances become smaller when the cobalt ion present in the solution. The charge transfer resistance of HER decreases with the increasing concentration of cobalt ion. The results of X ray diffraction (XRD), Energy Dispersive Spectrometer (EDS) and scanning electron microscopy (SEM) indicate that metallic cobalt electrodeposited on the surface of the electrode. As a result of the cobalt electrodeposition, the surface property of the cathode is changed significantly and thus the hydrogen evolution reaction is promoted. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.