The formation, stability and physico-chemical properties of TiO2 powders are strongly influenced by the actual synthesis and processing routes employed. Pure and metal-doped nanostructured TiO2 samples were obtained using the sot-gel method. In situ X-ray diffraction (XRD) experiments using synchrotron radiation were performed to explore the high-temperature/high-pressure stability and sintering behavior of these nanomaterials. The present results show a strong decrease of the anatase-to-rutile transition temperatures with increasing applied pressure, thus opening new perspectives for the development of efficient low-temperature sintering procedures. (C) 2003 Elsevier Science B.V. All rights reserved.