Cu oxide/polyvinyl alcohol (PVA) nanofibers were synthesized by sol-gel and electrospinning technique. The obtained Cu oxide/PVA nanofibers were heated to remove the PVA compound at 673 and 873K. The ultrafine Cu oxide nanofibers were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS). The SEM images showed that the Cu oxide nanofibers were successfully synthesized by electrospinning and calcination and the average diameters of the electrospun Cu/PVA nanofibers were 268.9 +/- 97.2 nm. After the nanofibers were calcined at higher temperature than rt, the morphologies of the nanofibers changed. XRD results indicated that the crystalline structure changed from amorphous phase to monoclinic CuO through cubic Cu2O. TEM images also verified the crystal phase of Cu oxide nanofibers. XPS spectra revealed that the thermal oxidation of Cu proceeded during calcination. (c) 2014 American Vacuum Society.