Poly(vinylidene fluoride)-derived ultramicroporous carbon with a specific surface area of 1012 m(2) g(-1) and a very narrow pore-size distribution peaked at 0.55 nm is investigated as electrode material for supercapacitors. The unique microstructure features enable the carbon to present not only a high gravimetric capacitance (264 F g(-1)) but also a high electrode density (0.826 g cm(-3)), resulting in an outstanding high volumetric capacitance of 218 F cm(-3) in 6 mol L-1 KOH aqueous electrolytes. However, the carbon shows a very small capacitance of less than 7 F g(-1) in 1 mol L-1 Et4NBF4/PC, which implies the pores are too small to be accessible even for the desolvated ions in the non-aqueous electrolyte. (c) 2012 Elsevier B.V. All rights reserved.