Orthorhombic V2O5 single-crystalline nanowires with diameters of 30-50nm, and lengths up to hundreds of micrometers, which was by far the longest 1-D nanostructure of vanadium oxide been fabricated, were synthesized on a large scale through a template-free mild and direct hydrothermal reaction between VOSO4 center dot xH(2)O and KMnO4. The ability of the oxidizing agent was testified to be the decisive factor in the successful fabrication of as-obtained ultralong orthorhombic V2O5 single-crystalline nanowires, which might be a superior cathode material for the lithium ion batteries.