Titanium oxide (TiO2) nanotubes prepared by electrolytic anodisation of a titanium electrode have been systematically heat treated to control the conversion of the as-prepared amorphous structure to nanocrystalline anatase and rutile. Raman spectroscopy revealed that the temperature of calcination is critical in determining the structure and crystallinity of the titania. X-ray Photoelectron Spectroscopy analysis shows the as-prepared film to consist mainly of oxide, although a small amount of fluoride contamination remains from the electrolyte. Organic components from post-anodising cleaning treatments were also present. Fluorine ions are gradually ejected fromthe anodic layer during annealing and the fluorine concentration is negligible in samples that are heat treated above 400 ±C. Choosing the appropriate annealing temperature allows the structure to be made up of defined proportions of anatase and rutile with a reduced contamination of species from the electrolyte or organic solvents. Copyright°c 2010 JohnWiley & Sons, Ltd.