The transport of methanol through a commercially available perfluorinated ion‐exchange membrane containing an aqueous 1N sulfuric acid solution is characterized. To accomplish this task, a mathematical model capable of simulating quantitatively methanol‐transport experiments is developed, and an optimization routine is employed to obtain physicochemical coefficients for the system by comparing experimental and theoretical results. The chemical environment employed in this work is similar to that which is present in a methanol fuel cell. Perhaps most important, results of this work illustrate that methanol readily transports across the perfluorinated membranes—consequently, new membrane systems should be investigated for methanol fuel cells.