Large-scale TiO2 nanowires were synthesized by simple and low cost solvothermal method and their photocatalytic activity was investigated. The nanowires had a single-crystalline structure and grew along the < 001 > zone-axis rutile phase. Using TiCl4 precursor, the TiO2 nanowires were formed with the low density, showed no visible light photocatalytic activity due to its large bandgap energy. Compared to the TiO2 nanowires grown using TiCl4 precursor, the well-aligned TiO2 nanowires grown using the mixed precursors of TiCl4 and Ti(OC4H9)(4) exhibited the higher density and the narrower bandgap energy which appeared to be the main reasons for observing the significantly enhanced photocatalytic activity under both UV and visible light irradiation. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.011206esl] All rights reserved.