The study on thermodynamics of anion exchange equilibrium for Cl− / I – and Cl− / Br − uniunivalent reaction systems were carried out by using four different anion exchange resins in chloride form. The equilibrium constants (K) were calculated for these systems at different temperatures by using Bonner et al. equation by taking in to account the mole fraction of ions in the resin phase. The K values were observed to increase with rise in temperature, indicating the endothermic ion exchange reactions. From the values of equilibrium constants at different temperatures, enthalpies for the above reaction systems were also calculated. The selectivity of different ion exchangers in chloride form towards I− and Br− ions were predicted on the basis of enthalpy values.