Fluorocarbon-modified　silica　membranes　were　deposited　on　gamma-Al2O3/alpha-Al2O3　supports　by　the　sol-gel　technique　for　hydrogen　separation.　The　hydrophobic　property,　pore　structure,　gas　transport　and　separation　performance,　and　hydrothermal　stability　of　the　modified　membranes　were　investigated.　It　is　observed　that　the　water　contact　angle　increases　from　27.2　+/-　1.5　degrees　for　the　pure　silica　membranes　to　115.0　+/-　1.2　degrees　for　the　modified　ones　with　a　(trifluoropropyl)triethoxysilane　(TFPTES)/tetraethyl　orthosilicate　(TEOS)　molar　ratio　of　0.6.　The　modified　membranes　preserve　a　microporous　structure　with　a　micropore　volume　of　0.14　cm(3)/g　and　a　pore　size　of　similar　to　0.5　nm.　A　single　gas　permeation　of　H-2　and　CO2　through　the　modified　membranes　presents　small　positive　apparent　thermal　activation　energies,　indicating　a　dominant　microporous　membrane　transport.　At　200　degrees　C,　a　single　H-2　permeance　of　3.1　X　10(-6)　mot　m(-2)　s(-1)　Pat　and　a　H-2/CO2　permselectivity　of　15.2　were　obtained　after　proper　correction　for　the　support　resistance　and　the　contribution　from　the　defects.　In　the　gas　mixture　measurement,　the　H-2　permeance　and　the　H-2/CO2　separation　factor　almost　remain　constant　at　200　degrees　C　with　a　water　vapor　pressure　of　1.2　x　10(4)　Pa　for　at　least　220　h,　indicating　that　the　modified　membranes　are　hydrothermally　stable,　benefiting　from　the　integrity　of　the　microporous　structure　due　to　the　fluorocarbon　modification.