Hydroxyapatite (Ca10 (PO4)6 (OH)2 is the most suitable biocompatible material for bone and tooth replacement, the HAp powder was synthesized using biological waste of Mussel-shell as calcium source and using di-ammonium hydrogen phosphate (NH4)2HPO4 as phosphate source. The grained powder of mussel shell was dissolved in diluted Nitric acid (HNO3) and di-ammonium hydrogen phosphate was slowly added to the mixture while retaining the pH at 10 with ammonium hydroxide (NH4OH), followed by microwave irradiation for 30 min. After the residue calcined at 900° C for 2h, then the HAp soaked in simulated body fluid (SBF) at 37°C for several period of time like 7, 14 and 30 days respectively. After the specific period of soaking; the remainder was collected, washed and dried at hot air oven. The processed powder was described by numerous investigative techniques.