A simple sol-gel precipitation technique to synthesize nano hydroxyapatite (HA) particles (similar to 30 nm) that show similar morphology, size and crystallinity to HA crystals Of human teeth is reported. Calcium nitrate tetrahydrate and potassium dihydrogenphosphate were used as calcium and phosphorus precursors, respectively. Double distilled water was used as a diluting media for HA sol preparation and ammonia was used to adjust the pH to 11. After aging, the HA gel was dried at 40 degrees C and calcined to different temperatures ranging from 200 to 600 degrees C. The dried and calcined powders were characterized for phase composition using X-ray diffractrometry, and Fourier transform infra-red spectroscopy. The particle size and morphology was Studied using Transmission electron microscopy. The particle size distribution analysis of HA powders showed skewed distribution plot. The phase and particle characterization studied above showed that HA calcined at 600 degrees C Simulate HA crystals of teeth. (C) 2009 Elsevier B.V. All rights reserved.