In this study, the Ti alloy substrate was simultaneously coated with TiO2 film and hydroxyapatite using micro-arc oxidation, a relatively new surface modification technique where thick, hard, and anticorrosive oxide coatings can be easily and cost-effectively fabricated. Pulsed DC power and various voltages were applied to the Ti alloy substrate. Citric acid, ethylene diamine, and ammonium phosphate were also dissolved as electrolytes followed by the dispersion of hydroxyapatite nanoparticles into those prepared electrolytes. The effects of the composition and applied voltage on the bonding strength, bioactivity, cell attachment and cytotoxicity were investigated. It was observed that the simultaneously coated TiO2 and hydroxyapatite samples showed improved bioactivity, cell attachment and viability, while maintaining the bonding strength between the coated film and substrate. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.