TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Properties: The composite has larger size than the pore of the organometallic complex by 4.3 Angstrom x 3.7 Angstrom . The composite material has electroconductivity of 10-5 S/cm or more at 100 degrees C or more. Preferred Complex: The organometallic complex consists of metal belonging to group 2A, 3A or transition metal and has repeating unit containing ligand(s) (I) consisting of aromatic compound having two or more groups which can be coordinated to the metal atom. The aromatic compound is 1H-indene, 2H-indene, indan, naphthalene, 1,2,3,4-tetrahydro-naphthalene, 1,4-dihydro-naphthalene, 1,2-dihydro-naphthalene, s-indacene, anthracene, phenanthrene, biphenyl, tetramethylbenzene or dimethylbenzene. The group coordinated to the metal is -COOH, -SH, CHS2H or -SO3H. The organometallic complex further contains ligand (II) comprising O, S, triethylenediamine or pyrazine. The organometallic complex is of formula: (MRL)n or (M2R2L)n.M=metal;R=ligand (I);L=ligand (II);andn=integer.The nitrogen-containing heterocyclic compound is oxadiazole, iso oxadiazole, benzoxazole, purine, pyrazole, imidazole, triazole, tetrazole, benzimidazole, benzotriazole, their derivatives, oligomers or polymers. EXAMPLE - (In g) aluminum nitrate (0.375) and 1,4-naphthalene dicarboxylic acid (0.108) were mixed in deionized water (10 ml), and the mixture was superheated at 180 degrees C for 1 day. The pH of the reaction solution during the reaction start was 2.5 and after the reaction completion was 2.0. The reaction solution was filtered after the reaction completion and washed with distilled water to obtain pale yellow powdery complex crystals having composition of formula: (Al(OH)(1,4-ndc))n with yield of 80%. The obtained crystals were heated for 2 hours at 150 degrees C to obtain porous complex. The obtained complex was superheated at 120 degrees C for 12 hours and imidazole was introduced into the pores of the complex by vaporization to obtain a composite material. The film formed using the obtained composite material had high proton conductivity.