Mordenite (MOR) and ferrierite (FER) membranes without any pinhole and crack were synthesized by a vapor-phase transport method. The permeance of H-2, He, CH4, N-2, O-2 and CO2 was determined at 290-400 K; which showed minimum with increasing temperatures for most cases. In the parallel diffusion model was proposed, molecules adsorbed in a micropore are assumed to diffuse in parallel through the central region of the pore and along the wall region of the pore. This parallel diffusion model accounts for the effect of pore Size of MOR and FER on the permeation and expresses the experimental data well. The interaction between gas molecules and pore walls are evaluated for each gas.