Durability is a major issue against the commercialization of proton exchange membrane fuel cells (PEMFC). Several mechanisms play an important role in the degradation of the cathode catalyst layer (CCL) by deteriorating the transport properties of reactants in the CCL mainly. A pseudo three-dimensional (P3D), two-phase, and non-isothermal model is used to study the effects of cell degradation on the transport properties of the CCL. Accuracy of the model is verified by comparing the polarization curves from the model with the experimental ones reported in the literature. The model is used to investigate the effects of CCL transport properties and agglomerate parameters on cell performance. Results demonstrate that the cell performance is improved for thinner ionomer film around agglomerates, smaller agglomerates, higher exchange current density, lower transport resistance and higher proton conductivity of the CCL. The transport parameters of the CCL are varied to fit the polarization curves to the experimental ones for an accelerated stress test. It is found that the transport resistances increase exponentially with the carbon loss in the CCL
