Fuel cells are complex devices build by parts with distinct functions. The project CRF-99 faces the problem of describing effectively the great heterogeneity of structural features, materials, chemo-physical properties of a fuel cell’s parts with the aim of predicting and optimizing the performance curve. For this has been developed the finite volume code “Modellazione Integrata di Celle a combustibile (MIC) “ for the numerical simulation of direct hydrogen (DHFC) and direct methanol (DMFC) fuel cells . In MIC code is implemented the modified Bernardi Verbrugge (MBV) which has proved to be numerically stable and highly accurate for the description of fuel cells’ performance curves.