The adsorption of 7-aminodeacetoxy cephalosporanic acid (7-ADCA) - cephalexin binary mixture in aqueous solution has been studied using polymeric resins of two different types as well as activated carbon. The adsorption intensity was found to be strongly dependent on the aqueous phase pH and this dependence could be interpreted from a model for neutral species adsorption in all cases. Single-solute isotherms for 7-ADCA and cephalexin were correlated with the Langmuir, Freundlich and Redlich-Peterson isotherm models, the Langmuir model being found to provide the best fit of the experimental data. The differences in adsorption affinities of the solute obtained for different adsorbents were interpreted from sorbent surface chemistry and morphological structure. Experimental binary-solute adsorption isotherms were compared with four different types of binary-solute Langmuir models using single-solute parameters. The results showed that the difference in saturation capacities affected the adsorption equilibrium. Furthermore, three types of binary-solute Langmuir models were converted into the kinetic form and one of them was used to calculate the association rate constants of 7-ADCA and cephalexin from experimental data. The adsorption rate curves for 7-ADCA and cephalexin appear to be typical of the first order kinetics.