A vacancy solution model based on the NRTL equation was derived and its validity was examined using experimental isotherms for adsorption of krypton and xenon on MS5A and activated charcoal adsorbents. The experimental adsorption isotherms of pure component of Kr and Xe on the adsorbents were successfully correlated with the vacancy solution model based on the NRTL equation. The experimental results for the adsorption equilibrium of Kr-Xe binary component systems on the MS5A and activated charcoal adsorbents were also examined using the model. The binary adsorption equilibria were well predicted by the vacancy solution model without parameter fitting. The optimization of parameters of the model in the binary systems resulted in better correlation of the binary adsorption equilibria.