Titanium oxide (TiO2) nanospheres were synthesized by using cathodic-plasma electrolysis method at low voltage of 70 V. The morphological, componential, and structural characterizations of the nanospheres were carried out in detail by using scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). It is found the nanospheres mostly have diameters in the range of 20–200 nm, and are in anatase, rutile, and oxygen-deficient phases. The nanospheres exhibit excellent optical absorption covering the wavelength range from 240 to 2600 nm. It is also found that the low voltage during plasma electrolysis could result in more anatase phases of TiO2. The mechanisms responsible for the nanosphere formation and the wide spectral absorption were also discussed.