CeO2 powder were prepared by a reflux method and ethylene glycol; water mixed solvent using cerium nitrate hexahydrate as a cerium source and ammonium hydroxide as a precipitant. The mixed solvent is the most critical factors affecting the particle size and crystalline phase. As a result, the precipitates exhibited an armophous phase and aggregates of very fine particles. The surface area of synthesized CeO2 powder were 171m^(2)g^(-1). Synthesized CeO2 powder were manufactured capacitor electrode and pre-doping Li-ion using zero voltage current (ZVC) except from irreversible capacitance. Cyclic voltammetery was used to analyze the redox reaction capacitance of CeO2 powder.