Poly (vinyl pyrrolidone) (PVP)/magnesium acetate composite fibers were prepared by electrospinning technique via sol-gel process. Magnesium oxide (MgO) submicrometer fibers (solid) and tubes (hollow) with diameter in the range of 100-400 nm were successfully prepared by calcinations of PVP/magnesium acetate composite fibers. The MgO submicrometer fibers and tubes were characterized using SEM, X-ray diffraction (XRD), and TEM analytical techniques. XRD results showed that the crystalline cubic MgO fibers were formed and their crystallinity was highly influenced by the calcination temperature. SEM and TEM results clearly showed the formation of hollow submicrometer tubes and solid submicrometer rods/fibers. The exact mechanism of the formation of MgO submicrometer tubes is not clear and further studies are needed to gain insight into the mechanism of formation.