The purpose of this paper is to summarize the effect of a chemical equilibrium between solutes on the interdiffusion phenomena in a ternary system. The relations among experimental mutual diffusion coefficients and the diffusivities of the actual species present in solution. The theory is extended to both non-ionic and ionic systems. A discussion of the concentration dependence of the four diffusion coefficients and of the sign of the cross-terms is given. The data of several ternary systems cyclodextrin-guest-water are presented to support the theoretical approach. All the interdiffusion coefficients collected were measured by the Gouy interferometric technique and were used to calculate the values of the binding constant. These values were found in good agreement with those obtained from calorimetric studies.