A steady-state mathematical model for the ordered cathode of proton exchange membrane fuel cells is developed to investigate the dependence of the cathode performance on the structural parameters of the catalyst layer. The model is based on the governing equations for oxygen concentration and potentials of the membrane and the solid phase, coupled by Tafel relation for the oxygen reduction reaction kinetics. The cathode current density optimization at a given electrode potential is presented with respect to nano-thread radius, porosity, platinum mass percentage, thickness, Nafion volume fraction and platinum loading of the catalyst layer. The simulation results suggest that small nano-thread radius is preferred. Except for quite low values as well as thin catalyst layers, porosity and platinum mass percentage have minor effects on cathode optimization. The cathode performance depends strongly on the catalyst layer thickness and additional attention should be paid to a thinner catalyst layer. The cathode can be efficiently optimized by increasing the highly sensitive parameters, Nation volume fraction and platinum loading, to a suitable value which must avoid significant loss of oxygen transport. (c) 2006 Elsevier B.V. All rights reserved.