Tailoring the morphological, chemical, and physical properties of vanadium oxides (VOx) is crucial to optimize their performance in current and future applications. The present contribution proposes a new route to obtain VOx nanofibers with different V4+/V5+ ratios and crystallinity. The method involves the exclusive electrospinning of water-free NH4VO3-saturated solutions including a reductant. Subsequent air-annealing under suitable conditions yields vanadium oxide fibers of 20-90 nm diameter and 10-50 m2/g surface area. The presence of the reductant gives rise to VOx nanofibers with a considerable proportion of V4+. Then, the right choice of the calcination heating rate and temperature permits to modify the V4+/V5+ ratio as well as the crystalline phase and crystallite size of the fibers. With the proposed methodology, long-range continuous single-phase orthorhombic V2O5 and monoclinic V3O7 nanofibers are obtained.