A fuel cell having a polymer electrolyte membrane containing fluorine atoms distributed along the polymer chains, and metal conductors and/or catalysts, is protected from fluoride ion degradation of the metal components by a fluoride ion sequestering agent fixed in the cell or flowing through the cell. In a preferred embodiment, the fluoride ion scavenger comprises a suitable number of azacrown moieties attached to polymer constituents in the electrolyte membrane or in electrodes.