Polypyrrole-modified electrode (PPy) and stainless steel (SS) electrode were assessed for inhibition of hydrogen evolution reaction (HER). The naked SS at a potential lower than -0.5 V exhibited strong HER, compared to the extreme inhibition of HER on PPy film. The much higher linear Tafel slope and two orders magnitude lower current density on PPy film than SS, further confirm the severe inhibition behavior of the former. Further analysis by cyclic voltammetry, Tafel polarization and electrochemical impedance spectroscopy consistently demonstrates a thicker PPy film was more beneficial for the inhibition of HER than a thinner PPy film. These results reveal that PPy film may be an efficiently strong barrier for the charge transfer and a potentially alternative inhibitor for HER, providing an effective strategy to increase the useful operation voltage windows and enhance the current efficiencies in the electrochemical reactions accompanied with competitive HER. (C) 2013 The Electrochemical Society. All rights reserved.