A relatively easy method to synthesize pure, stable, stoichiometric nano crystalline hydroxyapatite (Ca-10 (PO4)(6)(OH)(2), HAP). at low temperature by sol-gel route is presented. Equimolar solutions of Ca(NO3)(2)4H(2)O and (NH4)(2)HPO4 dissolved in ethanol were used in the synthesis at 85degreesC. The product was sintered at 400degreesC, 750degreesC and 1200degreesC. They were characterized by chemical analysis, XRD, FT-IR, SEM and TGA/DTG. The synthesized HAP was found to be stable up to 1200degreesC without any by-products. The SEM analysis indicated presence of pores in the crystal planes. These pores might be important for biomedical applications as they could enhance the adhesion between the natural and synthesized bone apatite. Dynamic Light Scattering analysis revealed the presence of nanocrystalline HAP of size 1.3 nanometer radius in the samples synthesized using this technique. (C) 2003 Elsevier B.V. All rights reserved.