Cathodic polarisation curves and impedance spectra for cobalt silicides Co2Si and CoSi2 in 0.5-2 M KOH at ambient temperature were obtained. It was shown that electrocatalytic activity of both silicides in hydrogen evolution reaction (HER) is higher than that of cobalt. The dependences of equivalent circuit elements on the electrode potential were analysed. The conclusion was made that the atomic hydrogen adsorption on the surface of cobalt silicides is described by the Langmuir isotherm, and hydrogen evolution proceeds through the Volmer-Heyrovsky mechanism (at alpha(1) not equal alpha(2) for Co2Si and alpha(1) = alpha(2) for CoSi2; alpha(1) and alpha(2) are the transfer coefficients for the Volmer and Heyrovsky steps respectively). The Heyrovsky reaction is probably the rate-determining step. The values of the kinetic parameters of HER on Co2Si and CoSi2 in 1 M KOH were estimated. (C) 2015 Elsevier Ltd. All rights reserved.