Vanadium pentoxide nanofibers (VNF) and polyaniline nanofibers (PANF) nanofibers are synthesized by electrospinning and rapid chemical polymerization routes, respectively. The electrochemical performances of synthesized nanofibers are evaluated in symmetrical (VNF-VNF, PANF-PANF) and asymmetrical (VNF-PANF) configurations in aqueous KCl (3 M) medium by cyclic voltammetry (CV) and galvanostatic measurements. Both VNF and PANF fibers exhibits pseudocapacitive behavior at the electrode/electrolyte interface. The VNF-PANF asymmetrical device is capable of delivering an energy and power densities of 26.7 Wh kg (1) at 0.22 kW kg (1), respectively which is higher than that of symmetrical configuration of VNF-VNF (5.2 Wh kg (1) at 0.22 kW kg(-1)). In addition, VNF-PANF asymmetrical supercapacitor retained 73% of specific capacitance after 2000 cycles. These results clearly shows that high energy density supercapacitor can be constructed utilizing transitional metal oxides with conducting polymers as electro-active materials in an asymmetrical configuration in aqueous medium. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.040209jes] All rights reserved.