Carbon nanofibers (CNF) are synthesis by pyrolysis of polyacrylonitrile (PAN) nanofibersthat are prepared by dissolving of PAN in N,N-dimethylformamide (DMF) solution followed by electrospinning and drying.The obtained CNF are further treated via a CO2 activation process.The morphology and porous attribute of the resulting nanofibers are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N2 sorption measurements.Effects of polymer solution concentration and static voltage on the morphology and diameter of nanofibers are studied.Their unique microstructural features enable the ACF to present outstanding high specific capacitance in aqueous, non-aqueous and novel ionic liquid electrolytes.The result shows that the CO2 activated carbon nanofibers(ACNF) have average diameter (~ 300 nm) and a high specific surface area up to 2866 m2 g-1 which is three times higher than that of the raw carbon nanofibers.Together with the high surface areas and outstanding electrical conductivity, the resulting activated carbon nanofiberscould have further application in supercapacitor electrode materials.