We herein report a new class of high-temperature proton exchange membranes comprised of poly(acrylic acid-graft-hexadecyltrimethylammonium bromide) (PAA-g-CTAB) or poly(acrylic acid)-graft-poly(ethylene glycol) (PAA-g-PEG) hydrophobic hydrogel caged H₃PO₄. The membranes exhibit reasonable proton conductivity, enhanced H₃PO₄ retention ability and low solubility in water, making them promising as potential high performance and robust electrolytes for high-temperature proton exchange membrane fuel cells. Although the proton conductivity is still lower than that of H₃PO₄ doped PBI membranes, the new concept provides a different approach to proton exchange membranes for acid retention.