Hydrothermally　stable　silica-alumina　composite　membranes　were　synthesized　through　chemical　vapor　deposition　(CVD)　of　tetraethylorthosilicate　(TEOS)　and　aluminium　tri-sec-butoxide　precursor　at　923　K　on　porous　alumina　supports.　The　membranes　showed　high　hydrogen　permselectivity　(order　of　10−7　mol　m−2　s−1　Pa−1)　comparable　to　that　of　pure　silica　membranes　but　with　superior　hydrothermal　stability,　and　were　used　in　a　membrane　reactor.　The　permeation　of　small　gas　species　(H2,　He,　Ne)　was　well　explained　by　a　solid-state　diffusion　mechanism,　involving　jumps　of　the　permeating　species　between　solubility　sites.　The　permeation　mechanism　of　large　gas　molecules　(CH4,　CO2,　N2)　was　explained　by　the　gas　translation　mechanism　involving　large　pore　defects.　Steam　methane　reforming　(SMR)　on　a　Ni/MgO-SiO2　catalyst　was　carried　out　at　923　K　in　the　membrane　reactor　and　in　a　conventional　packed-bed　reactor.　The　membrane　contributed　to　an　increase　in　the　hydrogen　production　rate　by　the　selective　extraction　of　hydrogen　from　the　reaction　zone.　©　2017　Elsevier　B.V.