Petroleum- based needle coke was activated by KOH to develop high-performance activated carbons as carbon electrodes for an electric double- layer capacitor ( EDLC). The effect of preparation parameters on the properties of activated carbons was investigated, and their EDLC properties were measured in an organic electrolytic solution. As-prepared activated carbons ( NCD- ACs) exhibit large surface areas ( 400- 2900 m(2)/ g), high EDLC capacitances (14- 44 F/g), and low system resistances (8.3- 18.7 Omega) on the basis of the anisotropic texture of their precursor.