Breakthrough curve measurements of SO2 and water vapor were carried out on a number of selected mordenite and pentasil zeolites from their binary and ternary mixtures with CO2 at 50 and 100 degrees C. SO2 capacities of these samples were found to be significantly reduced by the presence of water. Competitive adsorption led to unusually high overshoot peaks of SO2 breakthrough curves. On the other hand, SO2 was found to displace water on the samples with very high silica to alumina ratio. A linear driving force, isothermal model was used to predict the breakthrough curves. Langmuir and extended Langmuir equilibrium models were used to describe the equilibrium properties of water and SO2, respectively. The overall mass transfer resistance obtained from the model was compared to the values calculated from a simplified biporous adsorbent model to shed some light on the adsorption kinetics.