Ultrahigh-aspect-ratio V2O5 nanowires were successfully prepared using [ VO(O-2)(2)(OH2)](-) as the starting material by a template-free hydrothermal route without the addition of organic surfactant or inorganic ions. The prepared samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmet-Teller (BET), cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD). The results revealed that the peroxovanadium (V) complexes can be easily transformed to V2O5 nanowires by this hydrothermal route. The uniform nanowires were with width about 50 nm and length about dozens of micron. The BET analysis showed the V2O5 nanowires had a high specific surface area of 25.6 m(2) g(-1). The synthesized V2O5 nanowires performed a high capacitance of 351 F g(-1) when used as supercapacitor electrode in 1 mol L-1 LiNO3. (C) 2015 Elsevier B.V. All rights reserved.