A simple physical model for impedance of the cathode catalyst layer (CCL) in PEM fuel cell is solved analytically in the Tafel regime for small, but non-vanishing cell current densities (between 10 and 100 mA cm(-2)). Analytical results make it possible to obtain the Tafel slope, the double layer capacitance and the CCL proton conductivity from a single impedance spectrum without fitting. The method is illustrated with the experimental spectrum taken from literature. (C) 2012 Elsevier B.V. All rights reserved.