A transient physical model for the PEM fuel cell cathode catalyst layer (CCL) with fast proton and slow oxygen transport is solved and an analytical expression for the oxygen transport impedance is derived. This expression is combined with the proton transport and faradaic impedances of the PEMFC cathode reported previously. The resulting analytical impedance includes there action activation and the proton and oxygen transport losses in the CCL. Validity of this impedance up to the typical working cell currents on the order of several hundred mAcm(-2) is demonstrated by fitting the model equation to numerical impedance spectra calculated from the full system of conservation equations. (C) 2016 Elsevier Ltd. All rights reserved.