Progress on the development of a performance model for molten carbonate fuel cells is reported. Key physical and chemical phenomena being modeled include mass transport, ohmic losses, electrode kinetics, fuel and oxidant utilization, and convective heat transfer. Numerical schemes have been developed and programmed to calculate overpotential versus current density curves for individual electrodes, the cell current density distribution, and the cell temperature distribution, neglecting the effects of in-plane heat conduction.