Titanium oxide coatings are normally used for orthopaedic and dental prostheses. Nevertheless, their chemical, biological and mechanical properties can be still improved by the development of new preparation technologies. In this paper a surface characterisation of the titanium oxide layer, grown on commercial Ti substrates by metal organic chemical vapour deposition (MOCVD) technique, is reported. The biocompatibility of the samples is tested upon in vitro treatment as a function of the exposure time. The surface characterisation of the titanium substrate and the oxide coatings is performed by using different analytical techniques. Surface chemical composition and morphology of the coatings are investigated by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and scanning tunnelling microscopy (STM). Quantitative XPS analysis and surface physical images show a good quality (cleanness, homogeneity, roughness) of the oxide coating deposited by MOCVD and the surface modifications induced by the interaction with osteoblast cells.