A simulator has been developed to understand the behavior of a high temperature polybenzimidazole-based PEM fuel cell system. Polybenzimidazole (PBI) impregnated with phosphoric acid is proposed as an alternative to perfluorinated membranes (Nafion®). It operates above 100°C, which enhances the cathodic kinetic and increases the CO tolerance of the cell. The proposed model reproduces in a satisfactory way real experimental data obtained in the research of high temperature PBI-based fuel cells performance. Kinetic and mass transfer parameters fit in the range of typical values for this kind of fuel cells. This is an abstract of a paper presented at the 18th International Congress of Chemical and Process Engineering (Prague, Czech Republic 8/24-28/2008).