Background and purpose: The discharge of toxic heavy metal ions into the environment is a serious pollution problem. Heavy metal ions pose adverse toxic risks to human health at very low concentrations. The aim of this paper is the adsorption potential of chitosan (CS) in the removal of Hg(II) and Cd(II) ions from aqueous solution. Materials and Methods: This study was conducted in laboratory scale. In this research, CS was used as an adsorbent for the removal of Hg(II) and Cd(II) from aqueous solutions. In batch tests, the effects of various parameters such as metals concentration (40-350 mg/L), pH solution (2-8), contact time (5-120 min), and adsorbent dose (0.25-2 g) were investigated. Results: The results showed that adsorption of Hg(II) and Cd(II) ions on CS strongly depends on pH. The experimental data were analyzed using the Langmuir and Freundlich isotherm models. Equilibrium data fitted well with the Langmuir model and the maximum adsorption capacity of the CS for Hg(II) and Cd(II) were 52.63 and 58.8 mg/g, respectively. Kinetic analysis showed that adsorption was most accurately represented by a pseudo-second-order model. Conclusion: The obtained results showed that CS is a readily, available, economic adsorbent and was found suitable for removing Hg(II) and Cd(II) ions from aqueous solution.