In this work, the experimental characterization of gas diffusion material for PEM fuel cells is carried out. Properties such as porosity, capillary pressure curves, absolute permeability, and relative permeability were obtained for carbon paper Toray-090. Experimental fixtures and procedures used to characterize the porous material are presented. The effects of PTFE treatment (wet-proofing) and compression on the porous media properties were assessed. After characterizing the porous media material, two computational models of the air-cathode of a PEM fuel cell were developed using the gas diffusion media properties obtained. The hypothesis presented in this work is that cell performance can be accurately predicted using actual water transport characteristics of the GDL material instead of empirical correlations for well-sorted sands as reported by many authors.