Abstract: Immobilization of dithizone onto biopolymer chitin isolated from prawn seawater shells (P. merguensis) to enhance the selectivity and ability of chitin in adsorbing heavy metal cadmium (Cd) has been conducted. The study includes isolation of chitin from the prawn seawater, immobilization of dithizone onto chitin and adsorption of Cd(II) ions. Several parameters influencing immobilization as well as Cd(II) adsorption were optimized. Results of the study showed that high purity chitin polymer can be isolated from the prawn seawater shells (P. merguensis). The best immobilization conditions of dithizone onto chitin are achieved when the reaction is carried out for 6 h at 70oC in toluene medium. In general, the ability of chitin polymer in adsorbing Cd(II) ion increases after immobilization of dithizone onto chitin. The optimum conditions for Cd(II) adsorption are at pH 6 for chitin-dithizone and pH 7 for chitin using 0.3 g of adsorbent...