The equilibirum and kinetic characteristics of a MTES (methyltriethoxysilane) templating silica/α-alumina composite membrane were studied using unsteady and steady-state permeation of pure CO2, N2, CH4, H2, and He gases. The saturated amount of adsorption, Langmuir parameter, and diffusivity could be estimated by the generalized Maxwell-Stefan model, the incorporating dust gas model, and the Langmuir model using transient and steady-state measurements. The experimental and theoretical studies were extended to multicomponent gas mixture separation from single gas permeation. Since the permeation flux in the MTES membrane was affected by molecular sieving effects as well as surface diffusion properties, the kinetic and equilibrium separation should be considered simultaneously in the membrane according to molecular properties. All mathematical simulations and parameter estimations were performed by gPROMS dynamic simulator. This is an abstract of a paper presented at the 2006 AIChE National Meeting (San Francisco, CA 11/12-17/2006).