In this work we prepared a-alumina hollow-fiber supported SSZ-13 and ZSM-5 membranes by hydrothermal secondary growth. The effects of support surface roughness and porosity, zeolite topology and zeolite film thickness on the thermal behavior of composite membranes during detemplation were investigated. The quality of prepared membranes was characterized by SEM, single and mixture gas permeation tests and adsorption-branch permporometry. The surface roughness of a-alumina hollow fiber supports is shown to strongly influence the thermal stability of zeolite films. SSZ-13 and ZSM-5 membranes prepared on supports with rough surface could be safely detemplated without formation of cracks by calcination (450-500 °C), whereas membranes prepared on very smooth surface supports were cracked under similar conditions. In such case ozonication at lower temperature was found to be effective to detemplate the membranes without formation of cracks.