Metal-organic frameworks (MOFs) exhibit a huge potential for gas separation. ZIF-8 is an interesting candidate due to its high thermal stability and its pore properties. By liquid phase epitaxy, the growth of the highly oriented surface-anchored MOF ZIF-8 on non-porous and porous surfaces has been proven. The preparation of monolithic ZIF-8 thin films supported by porous alpha-Al2O3 substrates modified by a thin layer of Au is investigated. The layer-by-layer deposition process accomplished via a dipping procedure results in the formation of defect- or crack-free membranes, preliminary characterized by the determination of ethane and ethene permeance.