Nanoporous hydroxyapatite was synthesized utilizing cationic surfactants as templates. The effects of cetyltrimethylammonium bromide and reaction temperatures on the phase and morphology of HA were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). The thermal stability of nanoporous structures was studied by XRD and thermal analyzers (TGA/DTA), while the pore structure of HA was observed using high resolution TEM. It was found that the pore size was about 1 nm, and the pore structure of HA was thermally stable up to 700 T and the pore size did not change with reaction temperature and CTAB:PO43- ratio. The possible formation mechanism of nanoporous structure was proposed. (C) 2007 Elsevier Ltd. All rights reserved.