Elongated TiO2 nanoparticles with high aspect ratio have specific advantages in separation processes. In this study, TiO2 nanofiber was prepared via a hydrothermal reaction, and TiO2 nanoparticles with varied structural properties were obtained using hydrothermal and calcination post-treatments. Photocatalytic phenol degradation and Cr(VI) reduction over these catalysts was investigated. Results showed that hydrothermally prepared TiO2 nanofiber consisted of titanate with high aspect ratio. Calcining the as-prepared TiO2 nanofiber at 400 and 600 degrees C led to the crystalline phase transformation from titanate to TiO2-B and to the presence of mixed crystalline phases composed of TiO2-B and anatase. In contrast, hydrothermal post-treatment results in the generation of pure anatase TiO2 nanoparticles. For photocatalytic phenol degradation, calcining the as-prepared TiO2 nanofiber resulted in an enhanced catalytic activity, where as TiO2 nanoparticles obtained by calcination post-treatment showed lower catalytic activities for photocatalytic Cr(VI) reduction compared to as-prepared TiO2 nanofiber. TiO2 nanofiber modified using the hydrothermal post-treatment, however, exhibited the highest catalytic activity among TiO2 nanoparticles examined for both photocatalytic phenol degradation and Cr(VI) reduction. Furthermore, TiO2 nanoparticles obtained by hydrothermal post-treatment showed the best sedimentation efficiency, highlighting its prominent potential as a readily separable and recoverable photocatalyst. (C) 2009 Elsevier B.V. All rights reserved.