We report the preparation of nanocrystalline anatase and ruble TiO2 from aqueous peroxotitanium complex (PTC) solutions and their characterization by powder X-ray diffraction (XRD), infrared spectroscopy, and Raman spectroscopy The phase evolution of TiO2 prepared using PTC derived from different precursors, ie., TiCl4 and titanium tetraisopropoxide (TTIP), is related to the nature of the intermediate steps. Phase-pure nanoanatase was formed in PTC solution derived from TiCl4, while a mixture of minor anatase and dominant nude were prepared from PTC when TTIP was used as precursor On the other hand, in the case of calcining PVC powders in air, a pure anatase phase of TiO2 was obtained, regardless of the precursor used Thus, the formation and attachment of hydrated TiO6 units or TiO(2)xH(2)O under a different environment, especially pH, plays a critical role in determining the phase during the crystallization of TiO2 (C) 2010 Elsevier Inc All rights reserved