A parametric equation describing polarization in solid oxide fuel cells (SOFC) in terms of experimentally measurable parameters is presented. The equation explicitly describes activation and concentration polarizations at the two electrodes and the ohmic loss as functions of current density. Using known values of parameters measured on cell materials and components, various polarizations are estimated as functions of current density and the possible performance characteristics are assessed. The calculated performance curves using measurements made on cell materials and components are in good agreement with actual fuel cell tests. Using the model, prospects for ultra-high power density SOFC at intermediate temperatures (<800 degrees C) are examined. The results show that even in thin electrolyte film anode-supported cells, the ohmic contribution can be substantial, not all of it being attributable to electrolyte and electrode materials. The results also show that the electrode particle size has a substantial effect on the activation polarization. (C) 2015 Elsevier B.V. All rights reserved,