Thin films of titanium oxide have been deposited on (100) silicon wafers and on quartz substrates by reactive r.f. magnetron sputtering from a 99.6% pure Titanium target. Amorphous and overoxidised coatings (TiO2.2) have been obtained from this technique. The influence of the post-deposition annealing between 300 degrees C and 1100 degrees C on the structural and optical properties and on the surface morphology has been investigated. The results of X-ray diffraction showed that films annealed from 300 to 500 degrees C have an anatase crystalline structure whereas those annealed at 1100 degrees C have a rutile crystalline structure. Optical analyses showed that UV-Vis transmission spectra are strongly modified by the annealing temperature and refractive index of TiOx layers also changes. Atomic force microscopy measurements corroborate optical and structural analyses and showed that the surface of the coatings can have various appearances and morphologies for the annealing temperatures investigated.