A quaternary ammonium salt modified chitosan magnetic composite adsorbent (CS-CTA-MCM) wasprepared by combination of Fe3O4 nanoparticles. Various techniques were used to characterize the molecular structure, surface morphology, and magnetic feature of this composite adsorbent. CS-CTAMCM was employed for the removal of Cr(VI) and methyl orange (MO), an anionic dye, from water in respective single and binary systems. Compared with chitosan magnetic adsorbent (CS-MCM) without modification, CS-CTA-MCM shows evidently improved adsorption capacities for both pollutants ascribed to the additional quaternary ammonium salt groups. Based on the adsorption equilibrium study, MO bears more affinity to CS-CTA-MCM than Cr(VI) causing a considerable extent of preferential adsorptionof dye over metal ions in their aqueous mixture. However, at weak acidic solutions, Cr(VI) adsorption isevidently improved due to more efficient Cr(VI) forms, i.e. dichromate and monovalent chromate,binding to this chitosan-based adsorbent. Thus chromium could be efficient removal together with MO atsuitable pH conditions. The adsorption isotherms and kinetics indicate that adsorptions of Cr(VI) and MOby CS-CTA-MCM both follow a homogeneous monolayer chemisorption process. This magnetic adsorbentafter saturated adsorption could be rapidly separated from water and easily regenerated using diluteNaOH aqueous solutions then virtually reused with little adsorption capacity loss.