NOVELTY - Hydrolysis condensation reaction of formaldehyde and resorcinol is carried out in presence of magnesium acetate, to obtain gelled composition. Then, the gelled composition is substituted by solvent chosen from acetone, methanol, and ethanol. The network structure in gel is reinforced by aging the solvent-substituted composition. The solvent in the aged composition is substituted by liquid carbon dioxide. Then, the composition is dried to obtain resorcinol-formaldehyde aerogel. The obtained aerogel is carbonized to obtain carbon aerogel.    USE - Production of carbon aerogel used for manufacturing electrode used for manufacturing supercapacitor (both claimed), fuel cell electrode material, catalyst, absorbent, rechargeable battery and secondary battery used for cellular phone and digital camera.    ADVANTAGE - The method provides carbon aerogel having favorable pore size and pore structure by simple process in short period of time. The supercapacitor formed using the carbon aerogel has high capacitance. The drying process is carried out without the breakage of pore structure formed inside the aerogel.    DETAILED DESCRIPTION - Magnesium acetate is added to mixed solution of formaldehyde and resorcinol and agitated. Then, hydrolysis condensation reaction of formaldehyde and resorcinol is carried out in presence of magnesium acetate at 25-90 degrees C, to obtain gelled composition containing network by bonding the clusters. Then, the gelled composition is substituted by solvent chosen from acetone, methanol, and ethanol. The network structure in gel is reinforced by aging the solvent-substituted composition. The solvent in the aged composition is substituted by liquid carbon dioxide. Then, the composition containing carbon dioxide supercritical state is dried to obtain resorcinol-formaldehyde aerogel. The obtained resorcinol-formaldehyde aerogel is carbonized, to obtain carbon aerogel. INDEPENDENT CLAIMS are included for the following:    (1) manufacture of supercapacitor electrode; and    (2) manufacture of supercapacitor.