The effect of temperature on the ion exchange equilibrium behavior of binary systems is studied experimentally and modeled. The study considers the exchange between binary systems involving Na+, K+, Ca2+ and Mg2+ ions with Cl- as a nonexchanging anion on Rohm and Hass gel-type Amberjet 1200H resin as the ion exchange medium. Experimental equilibrium data is obtained for the six constitutive binary systems at 4.0, 25.0 and 60.0 degrees C with a total solution concentration of 0.10 N. The nonidealities in the solution and exchanger phases are modeled by applying the Pitzer and Wilson models, respectively. Thermodynamic equilibrium constant and Wilson interaction parameters are modeled with respect to temperature. The model proposed allows the influence of temperature on the ion exchange equilibrium behavior to be predicted well.