The Integrated Planar Solid Oxide Fuel Cell (IP-SOFC) is an innovative fuel cell concept which is substantially a cross between tubular and planar geometries, seeking to borrow thermal compliance properties from the former and low cost component fabrication and short current paths from the latter. In this study, a simulation model for the IP-SOFC is presented, with particular highlight on the simulation of the local reaction, taking into account the chemical and electrochemical processes occurring at the electrodes, together with mass transport issues. Some aspects of the overall reactor simulation are discussed as well. The model results have been compared to the experimental data obtained from both a small scale IP-SOFC module and a full-size prototype; in both cases the agreement is good. This electrochemical model is the basis of a detailed model of the full-scale IP-SOFC reactor to be included into a plant simulation tool designed to support thermodynamic analysis of hybrid IP-SOFC/GT (Gas Turbine) systems.