SiC nanoporous membranes have been prepared by chemical-vapor deposition/chemical-vapor infiltration of two different precursors, namely tri-isopropyl si lane (TPS) and 1,3-disilabutane (DSB). Both precursors produce nanoporous membranes. The TPS-derived membranes are hydrothermally stable, while the DSB membranes produced, so far, are not. SiC nanoporous membranes have also been prepared by conventional dip-coating techniques using a novel pre-ceramic polymeric precursor allyi-hydridopolycarbosilane (AHPCS), a partially allyl-substituted hydridopolycarbosilane (HPCS). These membranes are stable in air-treatment at 450degreesC, but have, so far, also proven unstable to high-temperature steam. The nanoporous hydrogen selective SiC membranes show promise for application in membrane reactors for the water gas shift and steam reforming reactions. (C) 2004 Elsevier Ltd. All rights reserved.