Most of the actual orthopaedic devices, widely made of titanium and its alloys, present different weaknesses like ions release and risks of loosening over a long period. To solve such problems, new developments ill Surface modification are crucial. This work is an extension of our recent effort on the development and improvement of a Multifunctional inorganic/organic bilayers coating. A thin tantalum oxide layer is formed by sol-gel synthesis followed by the modification with organophosphonic acids of the tantalum oxide layer. We focus in particular on die effect of the bilayers coating oil corrosion resistance and hydroxyapatite growth rate by immersion in a simulated body fluid Solution. It is also highlighted that the structure of the organophosphonic acid is of major importance on the osteoinduction character of the material. (C) 2009 Elsevier Inc. All rights reserved.