A method for making a composite ion exchange membrane including fabricating a layered membrane precursor including a microporous support of highly fluorinated nonionic polymer adhered to a layer of highly fluorinated sulfonyl halide polymer, hydrolizing the layered membrane precursor to convert the highly fluorinated sulfonyl halide polymer to highly fluorinated sulfonate polymer, impregnating the microporous support with a dispersion of highly fluorinated sulfonate polymer or precursor thereof in a polar liquid medium after hydrolyzing, removing the polar liquid medium, and heating to coalesce the highly fluorinated sulfonated polymer in the support.