It has been assumed that cation electron coupled charge transfer can be conducted in accordance with two mutually coupled reactions. Using a differential method an expression was introduced which describes the impedance of a cation electron coupled transfer reaction. Also, an electrical equivalent circuit has been defined. The total faradaic impedance is the sum of electron transfer impedance and cation transfer impedance. Issues of potentiostatic and potentiodynamic impedance measurements have been discussed. The relationship between polarization resistance and impedance has been explained. Polarization resistance as well as direct current depend on potential scan rate. The electrode potential influence on impedance has been determined. (C) 2012 Elsevier Ltd. All rights reserved.