Rapid synthesis of calcium deficient hydroxyapatite (CDHA, Ca 10-x(HPO4)x(PO4)6-x(OH) 2-x) with Ca/P ratio 1.5 was done by precipitation using calcium nitrate tetra-hydrate and phosphoric acid and subsequently subjecting to microwave irradiation in a domestic microwave oven for 15 min. Transmission electron microscopy analysis shows needle like morphology of CDHA having length 16-39 nm and width 7-16 nm. The synthesized CDHA has the characteristic HPO 2- 4 vibration band at 875 cm-1 in Fourier transform infrared (FT-IR) spectra. The X-ray powder diffraction (XRD) analysis shows a pattern corresponding to stoichiometric hydroxyapatite (HA) with broad peaks suggesting that CDHA particles were nanosized. Fourier transform Raman spectroscopy (FT-Raman) do not indicate any fluorescence band that is characteristic of non-stoichiometric HA. The thermal decomposition of CDHA to beta tricalcium phosphate (β-TCP) was also studied for the additional confirmation. The nanosized CDHA was found to be stable up to 600°C. © 2004 Kluwer Academic Publishers.