A nano-sized hydroxyapatite (HA) layer was coated on a Ti substrate with a titanium oxide (TiO2) buffer layer by the electron-beam deposition method. The morphological features as well as the mechanical and biological properties of the HA/TiO2-layered coating were noticeably different from those of a conventional HA coating on Ti. The HA on the TiO2 layer replicated the fine grain structure of the TiO2 layer, with grain sizes of just a few tens of nanometers. The TiO2 buffer layer was highly effective in preserving the adhesion strength of the coating layer following the heat treatment at 500 degrees C, which was necessary to crystallize the structure. Moreover, in contrast to the HA single coating wherein severe cracking was observed under moist conditions, the HA/TiO2 coating retained its mechanical stability under the same conditions. The dissolution of the HA/TiO2 coating in a physiological saline solution exhibited a more favorable pattern than that of the HA single coating, with a reduced initial burst and a subsequent steady release rate. Preliminary in vitro cellular tests showed that osteoblastic cells expressed a significantly higher alkaline phosphatase level on the HA/TiO2 coating than on the HA single coating. Conclusively, the nano-sized HA coating with the TiO2 buffer layer holds great promise as a bioactive coating system.