Several electrochemical properties of the heat-treated toluene-insoluble fraction separated from fullerene-soot (Fs-TI) were investigated to find their application as an advanced electrical double-layer capacitor (EDLC) electrode material using an organic solvent electrolyte. The heat-treated Fs-TI at 900 degrees C (Fs-TI-900) showed as high as 58 F g(-1) of capacitance, which is ascribed to its high capacitance per unit surface area as well as its reasonable surface area. In addition, the capacitor cell with Fs-TI-900 electrodes exhibited a better rate stability than that with conventional active carbon fiber electrodes due to its high electronic conductivity. The material heat-treated at 2400 degrees C (Fs-TI-2400) showed much smaller capacitance than Fs-TI-900 due to its smaller surface area. A unique rate dependence of capacitance was observed when the ion size of electrolyte was varied. (c) 2005 Elsevier B.V. All rights reserved.