Steady-state single-component and ternary mixture xylene permeation fluxes through Ba-ZSM-5/SS composite membranes were studied, as a function of temperature and pressure. The single p-xylene flux has a weak maximum, relative to temperature (100-400 degrees C). The flux magnitude and its maximum location are dependent on the extent of Ba-exchange. The o- and m-xylene fluxes steadily increase with temperature. The single permeation behavior is well-described by a model based on the contribution of different transport mechanisms: Knudsen flux, surface diffusion, and activated gas translation diffusion. The comparisons between either the mixture permeation results or the pressure effect experiments and the simulated data reflect the existing adsorbate-framework interactions that are not easily contemplated by a macroscopic model.