Perfluorodecyl-modified　silica　membranes　were　prepared　by　the　sol-gel　technique　using　tetraethyl　orthosilicate　(TEOS)　and　1H,1H,2H,2H-Perflouorodecyltriethoxysilane　(PFDTES)　as　precursors　under　acidic　and　clean　room　conditions.　The　wettability　and　pore　structure　of　the　modified　silica　membranes　were　characterized　by　means　of　water　contact　angle　measurement,　Fourier　translation　infrared　spectroscopy　(FT-IR),　solid　state　Si-29　magic　angle　spinning　nuclear　magnetic　resonance　(29Si　MAS　NMR)　and　nitrogen　adsorption.　The　membrane　performances　including　gas　permeation/separation　and　long-term　hydrothermal　stability　were　also　investigated　in　detail.　The　results　show　that　perfluorodecyl　groups　have　been　successfully　incorporated,　resulting　in　a　transformation　from　hydrophility　to　hydrophobicity　for　the　modified　silica　membranes.　With　a　low　PFDTES/TEOS　molar　ratio　of　0.2,　the　modified　silica　membranes　exhibit　a　water　contact　angle　of　112.6　+/-　0.5　degrees　and　a　pore　size　ranging　from　0.45　to　0.9　nm.　The　hydrogen　permeance　increases　with　increasing　temperatures,　leading　to　a　considerably　high　value　of　9.71　x　10(-7)　mol　m(-2)　s(-1)　Pa-1　at　300　degrees　C.　At　such　a　temperature,　the　H-2/CO2　permselectivity　and　binary　gas　separation　factor　are　7.19　and　12.11,　respectively.　Under　a　humid　condition　with　a　temperature　of　250　degrees　C　and　a　water　vapor　molar　ratio　of　5%,　the　single　Hy　permeance　and　H-2/CO2　permselectivity　remain　almost　constant　for　at　least　200　h,　indicating　that　the　modified　membranes　possess　an　outstanding　hydrothermal　stability.　(C)　2014　Elsevier　B.V.　All　rights　reserved.