The effects of electrode thickness, electrolyte filling and current collector geometry on the performance of MCFC cathodes are investigated by using a steady state mathematical model. A two-dimensional pseudo-homogeneous model for the three-phase system in the cathode is used, which includes the polarisation curves from the heterogeneous agglomerate model[1] as local source functions. The model takes into account the potential distribution in the electrolyte and catalyst phase but neglects mass transport limitations in the gas phase. The simulations show that, for cathodes with a finite electronic conductivity, there is a substantial potential distribution perpendicular to the depth of the electrode depending on the size of the gas holes in the current collector.