Poly(acrylonitrile) (PAN) solutions in dimethylformamide (DMF) were electrospun into webs consisting of 300 nm ultrafine fibers. High-surface area carbon nanofiber webs were prepared by oxidatively stabilized electrospun PAN fibers, followed by activation at 800 degrees C with steam for different times. The specific surface areas of samples ranged from 460 to 1160 m(2)/g. The specific capacitances from the samples ranged from 133 to 75 F/g, depending on the activation time. The results provided a simple and economical means that could substantially enhance the capacitance of the carbon materials. (C) 2004 The Electrochemical Society.