Oxygen transport resistance in the cathode catalyst layer of polymer electrolyte fuel cells is discussed. The performance of the cell is first calculated using a 1-dimensional through-plane model in which the activation overpotential and the diffusion-limited current density are fitted to experimental results. Potential-dependent transport resistance is then introduced to bridge the gap between the model prediction and the experimental result in the intermediate potential region. The potential dependent resistance is discussed using an oxygen transport model near the ionomer-Pt interface, where the coverage of adsorbed species changes with the potential. The oxygen transport model predicts that the diffusion layer near the interface is thinner than the thickness of the ionomer that covers the Pt nanoparticles. (C) The Author(s) 2018. Published by ECS.