TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Path: The proton conduction path is formed by connecting gap between particles from main surface to opposing surface of proton-conductive film.Preferred Structure: The metal-oxygen cross-linked structure is silicon-oxygen cross-linked structure.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Path: The proton conduction path is formed by connecting gap between particles from main surface to opposing surface of proton-conductive film.Preferred Structure: The metal-oxygen cross-linked structure is silicon-oxygen cross-linked structure.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Radical: The acid radical is sulfonic acid group.Preferred Properties: The particles have average particle diameter of 3-200 nm. The one-dimensional swelling rate of the proton-conductive film is less than 3%, after immersing into water and drying.Preferred Composition: The gap contains 3-50 mass% of water by dry mass.Preferred Particle: The particle has acidic-radical-containing structure (A) of formula (1), cross-linked structure (B) of formula (3) or cross-linked structure (C) of formula (4). The particle having structure (1) contains 3% or more of silicon atom.(X)n(R23-n)Si(R1)-SO3H (1)Si(X)n(R3)4-n (3)(R4)n-Si(X3-n)-R4-Si(X3-n)-(R4)n (4)X=-O- bond or OH;R1=20C or less hydrocarbon group, preferably saturated alkylene of formula (2): -(CH2)n-, where n is 1-30;R2=CH3, C2H5, C3H7 or C6H5;n of formula (1)=1-3;R3=20C or less alkyl;n of formula (3)=2-4;R5=molecular chain having 1-30 carbon atoms;R4=CH3, C2H5, C3H7, C4H9 or C6H5; andn of formula (4)=0-2.Preferred Film: The proton conductive film is manufactured using a basic catalyst chosen from amine or ammonium salt, preferably ammonia, triethyl amine, dipropyl amine, isobutyl amine, diethyl amine, diethanol amine, triethanol amine, pyridine, piperazine or tetramethyl ammonium hydroxide, and more preferably potassium fluoride, ammonium fluoride, tetramethyl ammonium fluoride and/or tetraethyl ammonium fluoride.Preferred Compound: The polar controlling agent has structure of formula (5):-(CH2CH2O-)n-. The mercapto-group-containing compound is structure of formula (6), mercapto-group-containing condensation product of formula (7), or mercapto group-containing condensation product of formula (8).(R7O)Si(R23-n)-(R1)-SH (6)n of formula (5)=1-14;R7 of formula (6)=H, CH3, C2H7, C3H6, or C4H9;R1=20C or less hydrocarbon group, preferably group of formula: -(CH2)s-;s=1-20;R2 of formula (6)=same as R2 of formula (1);n of formula (6)=1-3;R7 of formulae (7,8)=H, CH3, C2H5, C3H6 or C4H9;R2 of formulae (7,8), R8 and R9=OH, OCH3, OC2H5, OC3H6, OC4H9, CH3, C2H5, C3H7, C4H9 or C6H5;andn of formula (7)=1-100;m of formula (8)=1-100.A cyclic or branched structure is formed by coupling O-Si with R2 of formula (7) and -Si with R7. A cyclic or branched structure is also formed by coupling O-Si with R2,R8,R9 of formula (8) and -Si with R7.Preferred Blend: The blend further contains a cross-linking agent having structure of formula (10 or 11).Si(R10)n(R3)4-n (10)(R4)n-Si(R103-n)-R5-Si(R103-n)-(R4)n (11)R3=20C or less alkyl;R10=OH, OCH3, OC2H5, OC3H6, OC4H9, OCOCH3 or Cl;n=2-4;R4=R2 of formula (1);R5=as defined above;andn of formula (11)=0-2. EXAMPLE - Sila-AceS-810 (3-mercapto propyl trimethoxy silane) (in g) (0.2), tetraethoxy silane (0.8), diethylene glycol (0.2), triethyl amine (0.6) and water (0.25) were dissolved in tetrahydrofuran (1.8 mL), and stirred at room temperature for 10 minutes. The mixture was poured into Petri dish, and Petri dish was covered with glass panel. The obtained membranous substance was left at room temperature for 3 days, and gelatinized. The gelatinized film was supplied into desiccators at 80degreesC for 12 hours, and heated at 120degreesC for 24 hours. The membranous substance was removed and immersed in water and 1N sulfuric acid. Unreacted substance, catalyst and polar controlling agent were extracted from the film. The resulting film was immersed in acetic acid (125 mL) and 30% hydrogen-peroxide solution (100 ml) of peracetic acid, and heated at 80degreesC for 1 hour. The film was removed from peracetic-acid solution, and the process was repeated thrice. Proton-conductive film having thickness of 200 microns was obtained in round shape. The film had excellent heat resistance, durability and dimensional stability.