High temperature proton exchange membrane fuel cells (HTPEMFCs) based on phosphoric acid-doped polybenzimidazole (PBI) have received wide attention over the past decade. As opposed to perfluorosulphonic acid polymers (e.g. Nafion), which only function properly when they are in a highly hydrated state within a limited temperature range (<100 C), phosphoric acid-doped PBI can function at elevated temperatures (100– 200 C) under anhydrous conditions.