For the purpose of exact prediction of multi-solute adsorption equilibrium from respective single-solute adsorption isotherms, we propose a new method which employs a modified Langmuir kinematic adsorption model, assuming that the adsorptive surface of the adsorbent is heterogeneous in energy of adsorption. The predictions of adsorption equilibria on activated carbon for ten kinds of aqueous solutions, involving two solutes, were performed. The prediction accuracy of the present method was the same or slightly better than the two modified Radke''s methods, which were proposed by Jossens et al.