Abstract In this research work natural bio polymer "chitosan" was synthesized using locally available fish shells and adsorption of copper by chitosan was studied. Synthesize of chitosan involved four main stages as preconditioning, demineralization, deprotenisation and deacetylation. Chitosan was characterized using Fourier Transform Infrared Spectroscopy (FTIR). The affinity of chitosan for cupper was studied using anhydrous CuCl 2 solution as the heavy metal solution containing Cu (II) ions. Adsorption of cupper ions by chitosan was investigated under different conditions. Amount of copper absorbed was evaluated using atomic adsorption spectroscopy