A commercially available hydroxyapatite (HA) was sintered for a number of sintering temperatures and times between 1150°C to 1350°C and 0 to 12 hours respectively. Full density was reached after sintering for 1.5 hours at 1250°C and a maximum microhardness of 4.9GPa was achieved after 6 hours at 1300°C. Significant grain growth occurred but did not seem to influence the microhardness observed. Significant decomposition was observed after sintering at 1350°C for 1.5 which lead to major decreases in microhardness. An activation energy for grain growth of 286 kJ.mol-1 was calculated which is substantially higher than that previously noted for HA.