The hydrogen evolution reaction (HER) on the stainless steel electrode in MnSO4-(NH4)(2)SO4 solution (MA solution) with and without SeO2 was studied by the linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and chronoamperometry. It was found that SeO2 could effectively inhibit HER, but the control step of HER was not changed. The apparent activation energy of HER was increased from 50.56 kJ mol(-1) to 58.83 kJ mol(-1) after adding 9.0 x 10(-4) mol SeO2. The charge transfer resistance of HER was also increased. The inhibitory process of SeO2 on HER could be explained as follows: Se (IV) was reduced to Se (0), the morphology and composition of electrode surface were changed evidently by the deposition of selenium. The results of SEM and XRD further indicate that the explanation of inhibitory process of SeO2 on HER in MA solution is reasonable. Copyright 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.