Activated carbon nanofibers (ACNFs) based on a polymer blend, which consists of polyacrilonitrile (PAN) and cellulose acetate (CA), were prepared by electrospinning and subsequent thermal treatment. The diameter of ACNF increased with increasing CA content. The electrical conductivity increased with the addition of CA due to a larger oxygen amount of CA molecules. The specific surface area and average pore diameter of CA-free ACNF (CP) were 742 m(2)/g and 2.0 nm, respectively, while those of 15 wt % CA-blended ACNF (15CP) increased to 1160 m(2)/g and 2.8 nm, respectively. The capacitance of CP was 141 F/g at 1 mA/cm(2), whereas that of 15CP increased to 245 F/g. This is why the CP is predominated by small surface area with microporosity, whereas the 15CP is affected by higher surface area with better mesoporosity due to the combination of electrospinning based on polymer blends and thermal treatment.