A method for evaluating the spatial distribution of an ionomer in a fuel cell MEA. The method includes embedding the MEA in an epoxy, and then slicing thin sections from the MEA. The sliced sections are then exposed to a titanium tetrachloride vapor that stains the epoxy. The stained sections are then viewed with, for example, a transmission electron microscope (TEM) where the lighter regions in the TEM image show the ionomer distribution.