Calcium and phosphorous containing titania layers on Ti6Al4V biomedical alloy were formed by micro arc oxidation (MAO) in an electrolyte containing calcium acetate and sodium phosphate, and then subjected to hydrothermal treatment (HT) in order to achieve improved biocompability with modified titania layer. Samples were hydrothermally treated in water solution whose pH was adjusted to 11.0-11.5 by adding NaOH, at 230 °C for 10 h and cooled in the autoclave. Surface morphology, microstructure, and phase composition of titania layer were investigated systematically before and after HT. Their biomimetic apatite inducing ability in a simulated body fluid (SBF) was investigated. The bioactivity tests of modified MAO surface on Ti6Al4V alloy showed a considerable improvement compared to the unmodified MAO surfaceCalcium and phosphorous containing titania layers on Ti6Al4V biomedicalalloy were formed by micro arc oxidation (MAO) in an electrolyte containing calciumacetate and sodium phosphate, and then subjected to hydrothermal treatment (HT)in order to achieve improved biocompability with modified titania layer. Sampleswere hydrothermally treated in water solution whose pH was adjusted to 11.0-11.5by adding NaOH, at 230 °C for 10 h and cooled in the autoclave. Surface morphology,microstructure, and phase composition of titania layer were investigatedsystematically before and after HT. Their biomimetic apatite inducing ability in asimulated body fluid (SBF) was investigated. The bioactivity tests of modified MAOsurface on Ti6Al4V alloy showed a considerable improvement compared to theunmodified MAO surface.