Titanium dioxide (TiO2) nanomaterials, as important photocatalysis materials, have been synthesized with many approaches. In this study, we reported the synthesis of TiO2 nanomaterials by reacting titanium isopropoxide with ethylene glycol under basic condition followed by calcination at high temperatures. The structural, optical, and photocatalytic properties of the TiO2 nanomaterials were studied with x-ray diffraction, Raman spectroscopy, transmission electron microscopy, differential scanning calorimetry, Fourier-transformed infrared spectroscopy, x-ray and ultraviolet (UV) photoemission spectroscopy, UV–vis diffusive reflectance, and photocatalytic decomposition of methylene blue. We found that the titanium ethylene glycolide decomposes at 330 °C and transforms into pure anatase TiO2 around 400 °C. The anatase phase further transforms into core/shell rutile/anatase TiO2 composite at 550 °C and displays the highest photocatalytic activity among the samples prepared. The high photocatalytic activity can be attributed to the improved charge separation at the rutile/anatase n/n junction interface and the high crystallinity of the sample after calcination.