ZnO nanofibers were fabricated by electrospinning of a solution containing ZnO precursor, polyvinylpyrrolidone and solvent. The polymeric component of nanofibers were completely decomposed, thanks to the calcinations process (from 350 to 650 °C), so to obtain polycrystalline ZnO nanofibers. The crystallinity of ZnO nanofibers improved with higher annealing temperature. The mean diameter of the ZnO nanofibers after an annealing at 550 °C resulted ∼50 nm. Furthermore, we investigated the zinc oxide nanofibers doubling the amount of zinc acetate in the starting solution. The as-spun and annealed ZnO/polyvinylpyrrolidone composite fibers were morphologically and structurally characterized by scanning electron microscopy, X-ray diffraction analyses, and UV/vis optical characterization. The possible application of the synthesized nanofibers as photocatalytic material for water treatment was checked, too. These results are reported and discussed.