Mutual diffusion coefficients were measured with the Gouy technique for two ternary systems: (A) α-cyclodextrin - polyoxyethylene 5 hexylether -water, a non-ionic system, and (B) α-cyclodextrin - sodium 1 hexylsulfonate -water, a ionic system.For both systems the four measured diffusion coefficients allow us to estimate the diffusion coefficients of the actual species present in solution, assuming for the inclusion constant the values obtained from calorimetric data.