A polysesquioxane composition, comprising (i) a polysesquioxane matrix comprising sesquioxane moieties comprising a metallic element; (ii) a hydrophilic component; and (iii) a proton-conducting component, is provided. The metallic element can be silicon, aluminum, titanium, zirconium, germanium, or a mixture of two or more thereof. The hydrophilic component can comprise an imidazole moiety, a pyrazole moiety, a benzimidazole moiety, a silanol moiety, a cyclodextrin, or two or more thereof, and the hydrophilic component can be covalently bonded to the polysesquioxane matrix. The proton-conducting component can comprise an inorganic Brønsted acid moiety. The polysesquioxane composition can be used as a proton exchange membrane in a fuel cell; as a component of a membrane electrode assembly; or as a sensor assembly in a potentiometric sensor.