Sintered bone is composed predominantly of hydroxyapatite (HA), which is a phase of calcium phosphate. The properties of porous hydroxyapatite (HA) produced by heat treatment of bovine femur bone were evaluated over different temperatures between 400oC and 1200oC. The sintered body was investigated by using a number of physicochemical methods such as scanning electron microscopy (SEM), SEM in combination with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD). The XRD results indicate that the annealing process enhanced the crystalline grade of HA phase in the bone matrices particularly when sintered above 700oC. There was no secondary phase formation in bones sintered between 600oC and 1000oC. However, decomposition of HA to form of β-TCP was observed during heating at high temperature which are 1100°C and 1200°C.