The Taylor dispersion technique was used to measure quaternary diffusion coefficients, D-123(11), D-123(22), D-123(33), D-123(12), D-123(13), D-123(21), D-123(23), D-123(31), and D-123(32), in aqueous solutions of 2-hydroxypropyl-beta-cyclodextrin (HP-beta CD) + KCl + caffeine (CAF) + water, and 2-hydroxypropyl-beta-cyclodextrin (HP-beta CD) + KCl + theophylline (THP) + water at T = 310.15 K at different carrier concentrations of 0.002, 0.005 and 0.010 mol . dm (3), for each solute. The behaviour diffusion of these multicomponent systems and the coupled flows occurring in the solution can be explained on the basis of salting-out effects, as well as the possible interactions between both (cyclodextrin + xantine) or (cyclodextrin + metal ion) interactions, lead us in this way to obtain a better understanding of the structure of these systems. (C) 2014 Elsevier Ltd. All rights reserved.