A neutral protic salt electrolyte and a protic-salt imbibed polymer electrolyte membrane exhibiting high ionic conductivity and thermal stability at temperatures greater than 100° C. without requiring additional humidification systems or hydrating water is disclosed. The protic salt is the neutral product of acids and bases for which the proton transfer energy lies in the range from 0.5 to 1.5 eV. A polymer electrolyte membrane having the general formula: wherein A is a repeating unit in the main chain, B is a crosslinker chain, C is an end group, YZ is a neutralized couple at chain end, IL is an ionic liquid, and NP is a nanoparticle which absorbs the protic liquid yielding membranes that combine high mechanical strength with high conductivity. The present polymer electrolyte membrane is useful in high temperature fuel cells for automotive, industrial, and mobile communication applications.