The kinetics of the exchange of chloride ions in an anion-exchange resin has been studied. The rate measurements were carried out by a potentiometric technique, and thus both the kinetic and the activation parameters of the reaction were determined. The results concerning the influence of the stirring velocity upon the fractional attainment of equilibrium prove that the diffusion of the C1‒ species into the resin beads plays an important role in the mechanism of the exchange reaction, although the exchange rate is chemical in its ultimate mechanism.