Abstract: The adsorption kinetics and equilibrium of H_2PtCl_6 on various types of alumina were studied,and IRSand DRS were used to characterize these supports before and after impregnating with H_2PtCl_6 solution.Thedata indicated that the uptake of H_2PtCl_6 on supports strongly depends on the Lewis acidity of alumina andthat the adsorption rate is controlled by pore diffusion for supports of high adsorption capacity.Relationshipbetween uptake and acidity is interpreted in terms of active hydroxyl groups on alumina.