The electrolytes were prepd. by dissolving sulfolane (10-60%) in the N-methyl-N-propylpyrrolidinium bis(trifluoro-methanesulfonyl)imide (MPPyrNtf(2)) ionic liq. at 35 degrees C and used for impregnating a corn. C fiber fabric. A separator was made of glass fibers. The set was placed in 0.5 inch type Swagelok connector. The capacitor (MPPyrNTf(2) to sulfolane ratio 1:1) was subjected to a cyclic charging/discharging (1000 cycles) at 25 degrees C or 90 degrees C and 2.5 V The decrease of capacity was 10-15% at 25 degrees C and 5-8% at 90 degrees C. The highest sp. capacity (160 F/g) was reached for 5 mA.