Properties of hydroxyapatite (HA) or fluorapatite (FA), such as bioactivity, biocompatibility, solubility, and adsorption properties can be tailored over a wide range by modifying the composition via ionic substitutions. This research aimed to prepare and characterize Mg-doped FA (Mg-FA) nanopowders. Mg-FA nanopowders with different Mg contents were prepared by sol-gel method. The designated degree of substitution of Ca(2+) by Mg(2+) in the mixture was determined by the x value in the general formula of (Ca(10-x)Mg(x)(PO(4))(6)F(2)), where x = 0, 0.25, 0.5, 0.75, and 1. X-ray diffraction (XRD), scanning electron microscopic (SEM), transmission electron microscopy (TEM), atomic absorption spectrophotometer (AAS) and Fourier transform infrared spectroscopy (FTIR) techniques were utilized to characterize the obtained powders. Results showed that Mg ions entered into the fluorapatite lattice and occupied Ca(2+) sites. The incorporation of Mg ions into the fluorapatite resulted in the decrease of the lattice parameters. The obtained powders had crystallite size of about 30-100 nm. (C) 2010 Elsevier B.V. All rights reserved.