Kinetics of the amorphous-anatase phase transition in single immobilized 5-nm TiO2 nanoparticles has been studied at temperatures between 400 and 1000 degrees C at the DORIS-III synchrotron source of Hasylab. The measurements indicate the anatase phase appearance at temperatures above 500 degrees C. No formation of rutile phase was observed. The transformation kinetics for each fixed temperature is rapid and completes within 5 min. The crystalline mass progressively increases with temperature and the full transformation into anatase polymorph is achieved above 800 degrees C. The results suggest higher surface energy of the anatase phase compared to amorphous one, which delays the crystallization process. (C) 2012 Elsevier B.V. All rights reserved.