A solvable physical model for impedance of the cathode catalyst layer (CCL) in a PEM fuel cell is developed. The model includes reaction activation and oxygen transport in the CCL; the proton transport is assumed to be fast. The expression for the CCL impedance Z is derived and represented as a sum of the charge-transfer Z(ct) and oxygen transport Z(ox) impedances. Availability of analytical expression for Z(ox) enables to suggest a simple equation for the total CCL impedance, which includes oxygen and proton transport losses. This equation accurately reproduces a much more cumbersome exact solution obtained in Electrochim. Acta, 147 (2014) 773. An expression for the summit frequency of the oxygen transport arc is obtained. (C) 2016 Elsevier Ltd. All rights reserved.