Abstract: Calcium carbonate nano particles were synthesized using precipitation method from cockle shells by employing chitosan as precursor. Synthesized Calcium carbonates were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Visible and FTIR Spectroscopy. The results were compared with commercial calcium carbonate nano particles. Cockle shells are the potential source of calcium carbonate. The materials used were naturally occurring and also from the byproducts of sea food industry. The adopted methods were cost effective and ecofriendly.