Anatase nanotube arrays were grown by anodization with high crystallinity and a well ordered nanotubular structure. Nanotubes were stable to 800 degrees C, and this enhanced thermal stability of anatase nanotube arrays (without Ti support) was related to the induced tensile strain/stress inside the nanotube wall. The anatase-to-rutile phase transformation of titania nanotube arrays induces a tensile stress inside the nanotube wall that increases the critical nucleation size of rutile phase, as opposed to a compressive stress usually occurred on the surface of titania thin films or nanoparticles. (C) 2011 Elsevier Ltd. All rights reserved.