This work presents a study on the effect of hydrothermal temperature and structure on the photocatalytic activity of TiO2 nanotubes (TNT) prepared using commercially available TiO2 nanoparticles (P25). From the results, it was found that a higher hydrothermal temperature led to an increase in the specific surface area, total pore volume, and the size of mesopores in TNT. Moreover, the TNTs synthesized by the hydrothermal method had a new structure, which was very different from the anatase and rutile structures found in P25. The TNTs synthesized at 150 degrees C had the highest specific surface area of 371 m(2)/g. However, the TNTs synthesized at 180 degrees C exhibited the best photocatalytic efficiency and dye adsorption capacity, as compared to other TNTs, resulting from their well-developed mesopores. Crown Copyright (C) 2014 Published by Elsevier B.V. All rights reserved.