Abstract: The results of adsorption of methylene blue from an aqueous solution on various samples of Fe+3 intercalated clays of the Navbakhor Deposit are presented. Comparative studies of the applicability of the Langmuir, Freundlich, and Dubinin-Radushkevich models for describing experimental adsorption isotherms of modified clays and their heattreated forms at different pH values of the medium are presented. The DubininRadushkevich isotherm model was used to calculate the free energy of methylene blue adsorption on intercalated systems.