A method for evaluating the composition of an MEA for a fuel cell. The method includes soaking the MEA in an unsaturated organic compound for a predetermined period of time, and then allowing the MEA to dry. The method then includes staining the MEA with osmium tetroxide (OsO4) in a closed container. The stained MEA is then encased in an epoxy. Thin sections of the encapsulated MEA are then prepared, and the sections are viewed through a transmission electron microscope. The stained MEA will show dark regions where the ionomer and carbon particles are located and lighter regions that are epoxy filled pores.