NOVELTY - Electrolytic membrane comprises: a polymer of a composition comprising a crystalline organic and inorganic porous composite; and at least one (hetero)aryl compound comprising 3,4-dihydro-2H-benzo(e)(1,3)oxazine compound (I) or (II), (1,3)oxazinane compound (III), 9-oxa-10-phospha-phenanthrene 10-oxide (IV), 6-phosphorosooxy-3,4-dihydro-2H-1,3-benzoxazine compound (V) and naphthalene compound (VI).    USE - The electrolytic membrane or electrode is useful for fuel cell (claimed), which is useful in pollution-free vehicles, power generation systems for home use, and portable electronic devices including mobile communication equipment, medical devices, military equipment, and space industry devices.    ADVANTAGE - The electrolytic membrane exhibits high conductivity, excellent tensile strength characteristics, and excellent processibility such as dimensional stability, and prevents leakage of a phosphoric acid due to high phosphoric acid retention and improves cell voltage characteristics. The electrolytic membrane provides fuel cell with excellent cell performances at high temperature (100 degrees C or higher) under non-humidified conditions.    DETAILED DESCRIPTION - Electrolytic membrane comprises: a polymer of a composition comprising a crystalline organic and inorganic porous composite; and at least one (hetero)aryl compound comprising 3,4-dihydro-2H-benzo(e)(1,3)oxazine compound of formula (I) or (II), (1,3)oxazinane compound of formula (III), 9-oxa-10-phospha-phenanthrene 10-oxide compound of formula (IV), 6-phosphorosooxy-3,4-dihydro-2H-1,3-benzoxazine compound of formula (V) and naphthalene compound of formula (VI).    R1-R4 = 1-20C alkyl, 1-20C alkoxy, 2-20C alkenyl, 2-20C alkynyl, 6-20C aryl, 6-20C aryloxy, 2-20C heteroaryl, 2-20C heteroaryloxy, 4-20C carbocyclic, 4-20C carbocyclicoxy, 2-20C heterocyclic (all optionally substituted), halo, OH, CN or H;    R5 = 1-20C alkyl, 1-20C alkoxy, 2-20C alkenyl, 2-20C alkynyl, 6-20C aryl, 6-20C aryloxy, 7-20C arylalkyl, 2-20C heteroaryl, 2-20C heteroaryloxy, 2-20C heteroarylalkyl, 4-20C carbocyclic, 4-20C carbocycloalkyl, 2-20C heterocyclic or 2-20C heterocycloalkyl (all optionally substituted);    R5a = 1-20C alkyl, 1-20C alkoxy, 2-20C alkenyl, 2-20C alkynyl, 6-20C aryl, 6-20C aryloxy, 7-20C arylalkyl, 2-20C heteroaryl, 2-20C heteroaryloxy, 2-20C heteroarylalkyl, 4-20C carbocyclic, 4-20C carbocycloalkyl, 2-20C heterocyclic, or 2-20C heterocycloalkyl (all optionally substituted);    R6 = 1-20C alkylene, 2-20C alkenylene, 2-20C alkynylene, 6-20C arylene, 2-20C heteroarylene, -C(=O)- or -SO2- (all optionally substituted);    A2-E2 = C or one or two A2-E2 is N or C;    R7R8 = ring, which is 6-10 cycloalkyl, 3-10C heteroaryl, 3-10C heteroaryl, 3-10C heterocyclic, or 3-10C heterocyclic;    A1 = 1-20C heterocyclic, 4-20C cycloalkyl, or 1-20C alkyl (all optionally substituted);    R9-R16 = 1-20C alkyl, 1-20C alkoxy, 6-20C aryl, 6-20C aryloxy, 1-20C heteroaryl, 1-20C heteroaryloxy, 4-20C cycloalkyl, 1-20C heterocyclic, halo, CN, OH or H;    R17, R18 = 1-20C alkyl, 1-20C alkoxy, 6-20C aryl, 6-20C aryloxy or chroman-6-ol group of formula (Va);    R19, R19a = 1-20C alkyl, 1-20C alkoxy, 6-20C aryl, 6-20C aryloxy, halogenated 6-20C aryl, halogenated 6-20C aryloxy, 1-20C heteroaryl, 1-20C heteroaryloxy, halogenated 1-20C heteroaryl, halogenated 1-20C heteroaryloxy, 4-20C cycloalkyl, halogenated 4-20C cycloalkyl, 1-20C heterocyclic group, or halogenated 1-20C heterocyclic group; either    R20R21R22 = R1a-N((CH2)-aa-(CH2)(O)-aa) (ww); or    R20, R21, R22 = TT or H;    TT = 1-20C alkyl, 1-20C alkoxy, 6-20C aryl, 6-20C aryloxy, halogenated 6-20C aryl, halogenated 6-20C aryloxy, 1-20C heteroaryl, 1-20C heteroaryloxy, halogenated 1-20C heteroaryl, halogenated 1-20C heteroaryloxy, 4-20C carbocyclic, halogenated 4-20C carbocyclic, 1-20C heterocyclic, or halogenated 1-20C heterocyclic group; either    R23R24R25 = ww; or    R23-R25 = TT;    R1a = 1-20C alkyl, 1-20C alkoxy, 2-20C alkenyl, 2-20C alkynyl, 6-20C aryl, 6-20C aryloxy, 7-20C arylalkyl, 2-20C heteroaryl, 2-20C heteroaryloxy, 2-20C heteroarylalkyl, 4-20C carbocyclic, 4-20C carbocycloalkyl, 2-20C heterocyclic, or 2-20C heterocycloalkyl (all optionally substituted); and    aa = linking site for connection with two or more neighboring groups of R20-R22 or two or more neighboring groups of R23-R25.    INDEPENDENT CLAIMS are included for:    (1) an electrode for a fuel cell, comprising a composition comprising the crystalline organic and inorganic porous composite and I-VI, or a polymer as a polymerization product of the composition; and    (2) the fuel cell comprising a cathode, an anode and an electrolytic membrane interposed between the cathode and the anode, where at least one of the cathode and the anode is the electrode and the electrolytic membrane is the electrolytic membrane.