A model for catalyst layer (CL) performance is used to determine optimal shapes of electrolyte content and catalyst loading through the CL thickness. The effect of optimization strongly depends on the dimensionless working current density (j) over tilde (0). At small (j) over tilde (0) characteristic to a hydrogen cell, the effect of cathode optimization is marginal, while at large (j) over tilde (0) typical for a direct methanol fuel cell, optimization of the anode doubles the CL performance. (C) 2012 Elsevier Ltd. All rights reserved.