The simulation of proton-exchange membrane fuel cells (PEMFC) may work as a powerful tool in the development and widespread testing of alternative energy sources. In order to obtain an adequate PEMFC model, (which could be used in the analysis of FC generation systems), it is necessary to define the values for a specific group of modeling parameters. The simulation results are strongly affected by the choice of such modeling parameters. Multiparametric sensitivity analysis is a tool that can be used to define the relative importance of the factors related to the model, because it encompasses the entire parameter space. This paper presents a sensitivity investigation of PEMFC electro-chemical models, and aims to determine the relative importance of each parameter on the model results.