TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preparation (claimed): Fluoro-type sulfonic acid group-introduced amorphous carbon is obtained by carrying out fluorination processing of amorphous carbon formed by heat-processing a compound containing carbon in concentrated sulfuric acid or fuming sulfuric acid.Preferred Properties: The sulfonic acid density in the amorphous carbon is 0.1-8 mmol/g. The proton conductivity of the amorphous carbon measured based on alternating current impedance method at 80degreesC and 100% humidity is 0.01-10 Scm-1. The sulfuric content and fluorine content in amorphous carbon is 0.3-40 wt.% and 0.1-50 wt.%, respectively. The elemental ratio of sulfur with respect to carbon at surface is 0.01-0.2, and the elemental ratio of fluorine with respect to carbon at surface is 0.01-0.5. At least one optoelectronic peak of sulfur (S2p) is detected at bond energy of 165-175 eV in X-ray photoelectron spectroscopy, and at least one optoelectronic peak of fluorine (F1s) is detected at bond energy of 675-695 eV. The diffraction peak of carbon surface (002) at half value width (2theta) of 5-30degrees is detected, in powder X-ray diffraction.Preferred Process: Fluorination processing of sulfonic acid group-introduced amorphous carbon is carried out by contacting with fluorine at -70degreesC to 200degreesC. The heat-processed component is subjected to cation exchange processing in a basic aqueous solution, proton exchange processing in aqueous acid, and water washing, before carrying out fluorination processing. EXAMPLE - D-glucose (in g) (40) was heated at 400degreesC among inert-air flow for 15 hours, to obtain blackish brown organic material powder. The obtained powder (100) was added to 15 wt.% fuming sulfuric acid (150 ml), and heated at 150degreesC for 15 hours among nitrogen atmosphere, to obtain black solid. The obtained black solid was washed with distilled water (300 ml) to obtain amorphous carbon with which sulfonic acid group was introduced. The resulting amorphous carbon was fed to a container, and evacuation was carried out at 150degreesC for 1 hour. The temperature was lowered to room temperature, and fluorine gas was introduced into the container. The container was heated to 150degreesC for 3 hours, and excess hydrogen chloride was removed. The resulting product was washed with distilled water (300 ml) to obtain fluoro-type sulfonic acid group-introduced amorphous carbon. The obtained fluoro-type sulfonic acid group-introduced amorphous carbon had fluorine content of 1 wt.%, sulfur content of 3 wt.%, and sulfonic acid density of 1.4 mmol/g. The elemental ratio of sulfur with respect to carbon at surface was 0.03, and the elemental ratio of fluorine with respect to carbon at surface was 0.05. At least one optoelectronic peak of sulfur (S2p) was detected at bond energy of 165-170 eV in X-ray photoelectron spectroscopy, and at least one optoelectronic peak of fluorine (F1s) was detected at bond energy of 680-690 eV. The diffraction peak of carbon surface (002) at half value width (2(~o)) of 10degrees was detected, in powder X-ray diffraction.