The preparation of hydroxyapatite coatings on alumina substrates by a sol-gel method was investigated. A mixed ethanol solution of Ca(NO3)2·4H2O and P2O5 was used as a dipping source. The samples were characterized by solid-state 31P nuclear magnetic resonance spectroscopy, differential thermal analysis, thermogravimetry, X-ray diffraction, scanning electron microscopy and infrared reflection spectroscopy. The coating obtained at 500°C had good hydroxyapatite crystallinity, adhesive strength of about 10 MPa and dense morphology. The coating obtained at 750°C also had good crystallinity and adhesive strength but porous morphology.