This study shows that carbide-derived carbons (CDCs) with average pore size distributions around 0.9-1 nm and effective surface areas of 1300-1400 m(2) g(-1) provide electrochemical double-layer capacitors with high performances in both aqueous (2M H2SO4) and aprotic (1M (C2H5)(4)NBF4 in acetonitrile) electrolytes. In the acidic electrolytic solution, the gravimetric capacitance at low current density (1 mA cm(-2)) can exceed 200 F g(-1), whereas the volumetric capacitance reaches 90 F cm(-3). In the aprotic electrolyte they reach 150 F g(-1) and 60 F cm(-1). A detailed comparison of the capacitive behaviour of CDCs at high current density (Lip to 100 mA cm(-2)) with other microporous and mesoporous carbons indicates better rate capabilities for the present materials in both electrolytes. This is due to the high surface area, the accessible porosity and the relatively low oxygen content, It also appears that the surface-related capacitances of the present CDCs in the aprotic electrolyte are in line with other carbons and show no anomalous behaviour. (C) 2008 Elsevier Ltd. All rights reserved.