A novel fabrication technique, i.e., electrostatic spray pyrolysis (ESP), has been used in this study to prepare calcium phosphate nano powders. Final annealing was done at 400 degrees C for 30 min in air. The hydroxyapatite-forming ability of the annealed powder has been investigated in Eagle's minimum essential medium solution. X-ray diffracton, field emission scanning electron microscope, energy dispersive X-ray spectroscope, and Fourier transform infrared spectroscope were employed to characterize the annealed powders after immersion. The powder with an amorphous structure induced hydroxyapatite formation on their surfaces after immersion for 15 days. (c) 2006 Springer Science + Business Media, Inc.