Highly ordered TiO2 nanotube arrays were successfully prepared by electrochemical anodization in a formamide-based electrolyte containing 0.5 wt.% NH4F and 2 vol.% H2O. The effects of the calcining temperature, the calcining time and the heating rate on the formation of the TiO2 nanotube arrays were investigated in detail. The morphological changes and phase transformations of the TiO2 nanotubes were analyzed by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. It was found that the calcining temperature and the calcining time determined the crystal phase, while the heating rate was only beneficial to altering the crystallinity. UV-vis diffuse reflectance spectroscopy was used to examine changes in the band gap energy. For applications to dye sensitized solar cells, a maximum conversion efficiency was achieved at 500 degrees C for 2 h with a heating rate of 10 degrees C/min, which is attributed to the highly crystalline anatase and the lower surface defect concentrations of the nanotubes. The optimum calcination conditions help to retard the electron recombination and allow higher dye absorption capacities, thereby increasing V-oc and J(sc). (C) 2012 Elsevier Ltd. All rights reserved.