Search for new, cheaper and effective adsorbents especially for textile and leather dye effluents are in constant progress. Batch experiments were carried out for the adsorption of Reactive Black 5 by varying the composition of Sorel Cement. The composition of MgO and MgCl2 are varied. Further the Sorel cement was doped with FeCl3 and its adsorption capacity investigated. The effect of initial dye concentration, pH, and temperature and contact time were studied. The equilibrium data were fitted into Freundlich and Langmuir adsorption isotherms. The adsorption efficiency and adsorption capacity factor were calculated. The composition doped with FeCl3 showed a higher adsorption capacity. Such composites can be used to remove other organic dyes also. The process is chemisorption which increased with temperature and so the rate and extent of adsorption increased. Kinetics studies were fitted into pseudo first order rate expression.