Clays, as montmorillonite (Mt), are able to expand and incorporate cationic biopolymers like chitosan (C), either by interlaminar or superficial adsorption, giving special properties of interaction and structure to the final compound. Also, these materials have low toxicity and are abundant in nature, making them potential low-cost adsorbents. This work focuses on the structure and dye adsorption of different Mt:C compounds, for the remediation of water. C of different molecular weights, easily obtained by gamma irradiation of C without further need of reagents, were used. Calmagite (CG), an irritant and persistent anionic azo dye used in complexometry, was chosen as model compound to carry out the adsorption experiments.