The theory and modeling of multistage electrochemical reactions with the participation of relatively stable intermediates are considered in this work. The kinetic equations for multistage electrode processes complicated by the transfer of intermediates between the near-electrode layer and bulk solution are derived and analyzed. Computer-aided modeling of the kinetics of such processes is performed. The effects of various factors on the rate of individual stages are established. The results of numerical simulation of the kinetics of a two-stage electrochemical reaction with a partial transfer of intermediates between the near-electrode layer and the bulk solution under the conditions of linear non-steady-state diffusion of reactants are analyzed by means of a similarity theory and dimensional analysis. The dimensionless complexes (similitude criteria) that characterize the electrochemical reactions under consideration are obtained.