Chitosan-glutaraldehyde / nano-montmorillonite composite has been successfully prepared. The structure of the prepared bio sorbent has been confirmedby Fourier transforms infrared spectroscopy (FTIR),transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The adsorption kinetics and isotherm behaviors of Hg(II) and acid yellow dye (A17) molecules onto the prepared chitosan nanocomposite had been studied and describedby pseudo-first, pseudo-second order and Langmuir, Freundlich isothermmodels, respectively. Experimental data exhibit high adsorption capacities equal 125 and 302 mg /g for Hg(II) and A17, respectively.