Equilibrium and kinetics of oxygen and nitrogen sorption in two different carbon molecular sieves (CMS) have been modeled. In both CMS materials, equilibrium characteristics are adequately described by the Langmuir model. However, for kinetics of sorption, one CMS followed classic Fickian diffusion, while the other sample did not. A mathematical model was developed which accurately describes both pure component as well as binary uptakes in both materials. Simple manipulation of the boundary condition of the diffusion process allows the model to accurately predict both Fickian and surface barrier diffusion. All parameters needed to estimate binary uptake rates are obtained from pure component uptakes and isotherms. In addition, the model predicts both pure component and binary diffusion rates with diffusion coefficients which are not concentration dependent.