Hierarchical porous titanium dioxide is of great interest as a potential photocatalyst material because of its enhanced mass transfer capability and light capture efficiency. Tuning of these nanostructures allows for the design of new photocatalysts with improved performance. In this study, we report the synthesis of hierarchically meso-macroporous TiO2 materials through a template-free aqueous technique. Controlled porous textures and crystalline structures of TiO2 were obtained by varying the pH of the starting aqueous solution and the method of crystallization. The catalytic efficiency of these materials was investigated using photodegradation of methyl orange and the results show that specific surface area, pore volume and crystallinity play a key role in the photocatalytic performance. The hierarchical titania prepared by the hydrothermal method at a pH of 2 has the highest efficiency with an apparent reaction rate of 9.10 x 10(-2) min(-1), surpassing that of Degussa P25, hence showing its promising potential in environmental remediation. (C) 2010 Elsevier B.V. All rights reserved.