A microarc oxidized (MAO) TiO(2)-based film containing Ca and P was prepared on titanium alloy. The structure and apatite-forming ability of the MAO film before and after chemical treatment (NaOH aqueous solution) and subsequent dehydration at 400 and 600 degrees C were investigated. Before and after dehydration, the surface of the chemically etched MAO film show the presence of anatase and amorphous phase with a honeycombed morphology composed of numerous nano-flakes (50-100 nm in thickness) and pores (100-200 run in size). The apatite-forming ability of the MAO film was improved greatly after chemical etching; however, that of the etched MAO film decreases after dehydration. The reason for this is that dehydrated Ca-Ti-O compounds on the surfaces of the etched and heat-treated MAO films are unfavorable for Ca ions release compared with the hydrous Ca-Ti-O compound on the surface of the etched MAO film. The decreased ability of Ca(2+) ions release further lowers the formation ability of Ti-OH groups produced via ionic exchange between Ca(2+) ions of the etched and heat-treated MAO films and H(3)O(+) ions in simulated body fluid. (c) 2008 Elsevier B.V. All rights reserved.