Pure titanium was hydrothermally treated in 0.1 mol/L MgCl₂ solutions with different pH at 200°C for 24hr in order to improve its bioactivity. Surface morphology, roughness, wettability and chemical composition were characterized with sophisticated equipment before and after treatment. Simulated body fluid immersion experiment was conducted to examine in vitro osteoconductivity. Hydrothermal treatment preserved the macro topography of polished substrates in spite nano-sized precipitations were observed and these surfaces showed superhydrophilicity. Magnesium titanate was formed on titanium surface after hydrothermal treatment in MgCl₂ solution, however, under high pH, Mg(OH)₂ precipitated from the solution. Typical apatite spheres were observed on hydrothermally treated samples after immersion in SBF for 2 days. However, the precipitation was depressed with increasing Mg amount incorporated into titanium surface. The hydrothermal treatment was a promising finial treatment for fabricating titanium implants with good bioactivity.