NOVELTY - Method of forming a polymer/zeolite nanocomposite membrane (A) comprises forming a zeolite nanocrystal (I) and a polymer source suspensions; combining the both suspensions; ultrasonicating the resulting solution; pouring the solution into a casting vessel; heating the solution until the solution is dry; heat treating the dried solution; cooling the casting vessel; and removing the formed polymer/zeolite nanocomposite membrane.    USE - (A) is useful for proton-exchange-membrane fuel cells (claimed). (I) are incorporated into polymer matrices for membrane separation applications like gas separations and in polymer-exchange-membrane fuel cells. (claimed).    ADVANTAGE - (I) are size-adjustable to match polymer-network dimensions. (A) has the potential to maintain high proton conductivity and low methanol cross over at a temperature up to 140degreesC; improves anode kinetics; reduces anode carbon monoxide poisoning; improves methanol oxidation efficiency; and reduces cathode over potentials in proton exchange membrane fuel cells.    DETAILED DESCRIPTION - Method of forming a polymer/zeolite nanocomposite membrane (A) comprises forming a zeolite nanocrystal suspension; forming a polymer source suspension; combining the zeolite nanocrystal suspension with the polymer source suspension; ultrasonicating the resulting solution; pouring the resulting solution into a casting vessel; heating the poured solution in the casting vessel until the solution is dry; heat treating the dried solution; cooling the casting vessel; and removing the formed polymer/zeolite nanocomposite membrane. INDEPENDENT CLAIMS are also included for:    (1) a method of forming zeolite FAU(Y) nanocrystals (I), comprising: (a) combining a solution comprising double de-ionized water, 25 wt % aqueous tetramethylammonium (TMA) hydroxide (TMAOH) solution, and an aluminum isopropoxide; (b) stirring the solution until it is optically clear; (c) adding and dissolving TMA bromide (TMABr) in the solution; (d) adding aqueous colloidal silica to the solution to form a completed solution; (e) sealing the completed solution; (f) aging and stirring the completed solution; and (g) heating and stirring the completed solution to form (I);    (2) a method of forming phenethyl functionalized zeolite FAU(Y) nanocrystals (II), comprising steps (a)-(d); adding a phenethyl trimethoxysilane to form a completed solution; and steps (e)-g to form the phenethyl functionalized zeolite FAU(Y) nanocrystals;    (3) a method of forming phenethyl functionalized zeolite BEA nanocrystals (III), comprising: step (a) (where the aqueous tetraethylammonium hydroxide solution is 35 wt.%); step (b), step (d) (where the aqueous colloidal silica is 30 wt.%); adding an phenethyl trimethoxysilane to form a completed solution; steps (e-g) to (III); or forming an aluminum precursor solution; forming a silica precursor solution; stirring the aluminum precursor solution until it is optically clear; combining the aluminum precursor and the silica precursor solutions to form a combined solution; mixing the combined solution together; sealing the combined solution to form a sealed combined solution; and reacting the sealed combined solution to form (III); and    (4) a proton exchange membrane fuel cell comprising an anode; a catalyst disposed on the anode; a polymer-sulfonic acid functionalized zeolite nanocomposite proton exchange membrane disposed adjacent the catalyst; a second catalyst disposed adjacent to the membrane; and a cathode disposed adjacent to the second catalyst.