We report a physics-based analytical model for low-current PEM fuel cell impedance, which takes into account oxygen transport in the channel. The model is fast: fitting the model impedance to the experimental Nyquist spectrum takes about 2 minutes on a 2-GHz notebook. In addition to the transport and kinetic parameters of the catalyst layer, fitting returns the oxygen diffusion coefficient in the gas-diffusion layer and the resistivity due to oxygen transport in the channel. Maple worksheet with the fitting procedure is available for download. (C) The Author(s) 2017. Published by ECS.