Nanocrystalline hydroxyapatite (HAP) powder was synthesized by a non-alkoxide sol-gel method. The prepared powder was characterized with STA, X-ray diffraction, Zetasizer and SEM microscopy. The effect of aging for 24h and heating time at 550 °C on crystallity, crystallite and particle size were studied through XRD, zetasizer and SEM. Results showed that the powder obtained after heating at 550 °C for 6h was composed of pure HAP with the estimated crystallite size and particle size of 9.3 nm and 503.6 nm.