Abstract: A crosslinkable polymer composition comprises an olefin copolymer or graft copolymer with hydrolysable saline groups and a silanol condensation catalyst, as well as a silane compound with at least one hydrolysable organic group. The polymer composition is characterized in that the silane compound has a compatibility with the polymer composition of at least 0.035 mole hydrolysable groups per 100 g polymer composition, and in that the silane compound is represented by the general formula: R.sup.1 (SiR.sup.2.sub.n X.sub.3-n).sub.m, wherein R.sup.1 is a monofunctional hydrocarbyl group having 13-30 carbon atoms, or a difunctional hydrocarbyl group having 4-24 carbon atoms, R.sup.2 is a hydrocarbyl group having 1-10 carbon atoms, X is a hydrolysable organic group, n is 0, 1 or 2, and m is 1 or 2.