Hydrothermal treatment was performed on a titanium plate for its surface modification to enhance its bioactivity. The titanium plate was autoclaved in deionized water (DW) or 0.05 mol/l NaOH solution at 120, 200 and 240 °C for 24 hr. The titanium surfaces autoclaved in DW were homogeneously coated with nano-sized particles and polygonal deposits with the sizes of several hundreds nanometers. The deposits were regarded as anatase according to the results of laser Raman spectroscopy (LRS). In the case of autoclaving in 0.05 mol/l NaOH solution, leaf-like, needle-like and pyramid deposits were observed on titanium surfaces and regarded to consist of anatase or brookite by LRS analysis. The formation of the deposits significantly depended on the autoclaving temperature. The deposits adhered on the titanium surface though a tape-test; the adhesion of the particle was found to be excellent.