Chemically and thermally treated bovine bone has been proposed as an alternative to bone grafts and synthetic bone substitutes. Fluorinated bovine hydroxyapatite (FBHA) was prepared by two different methods at low and high temperatures. The effect of reaction temperature and fluorine concentration on the crystal morphology, phase purity and functional groups were observed by X-ray diffraction (XRD) method and FT-IR spectroscopy. The XRD results indicted that [3 0 0] reflection peak was shifted towards higher angle due to fluorination. The a-axis dimensions of both the FBHA samples were found to be decreased with the fluorination. The FT-IR spectra of FBHA samples confirm partial fluorination into the hydroxyl group of bovine hydroxyapatite. The in vitro physiological stability study was performed in phosphate buffered saline (PBS) of pH 7.4 at 37 °C and the samples were found to be quite stable for about a month. These results suggest the tremendous potential of fluorinated bovine hydroxyapatite as a bone substitute due to their bioactive nature. © 2002 Elsevier Science B.V. All rights reserved.