Here, we report the synthesis and the study of gas-transport properties of crosslinked highly permeable copolymers from Si-containing norbornene derivatives. The initial high-molecular-weight copolymers were prepared via addition copolymerization of 3-trimethylsilyltricyclo[4.2.1.0(2,5)]non-7-ene (TCNSi1) with 3-triethoxysilyltricyclo[4.2.1.0(2,5)]non-7-ene (TCNSiOEt) in good or high yields using a Pd-catalyst. The obtained copolymers included up to 10 mol% of TCNSiOEt units bearing reactive Si-O-C-containing substituents. The crosslinking was readily realized by using simple sol-gel chemistry in the presence of Sn-catalyst. The formed crosslinked copolymers were insoluble in common organic solvents. Permeability coefficients of various gases (He, H-2, O-2, N-2, CO2, CH4, C2H6, C3H8, n-C4H10) in these copolymers before and after crosslinking were determined and the influence of the incorporated TCNSiOEt units as well as the crosslinking on gas transport properties were established. As a result, it was found that only a small reduction of gas-permeability was observed when TNCSiOEt units were incorporated into the main chains, and the copolymers were crosslinked. At the same time, the selectivity for C4H10/CH4 pair was increased. The suggested approach has allowed obtaining crosslinked polymers from Si-containing monomers without a loss of the main membrane characteristics. (C) 2019 Society of Plastics Engineers