An electrolytic capacitor including a positive foil, a negative foil and an intervening separator which contains a polymeric electrolyte composite. The polymeric electrolyte composite contains electrolyte in the matrix of copolymeric acrylic ester. The separator contains at least either one of rayon fiber and cotton linter. Or, other separator takes the form of several overlaid sheets, each of the sheet being made of a cellulose fiber. The above-configured electrolytic capacitors have the advantages of high withstanding voltage, high heat resisting property and long life.