In this paper the ring-opening cross-metathesis of silicon substituted norbornenes with ethene is reported. Silicon containing norbornenes could be selectively ring-opened via a cross-metathesis with ethene employing Ru-based catalysts (RuCl2-(PCy3)(=CHSiMe3) (3) or RuCl2(PCy3)(2)(=CHPh) (4)). It was also found that for the ethenolysis, the order of sequence of the individual reagents is of crucial importance. Under mild reaction conditions and by premixing of ethene and the catalyst before the silicon containing norbornene (C13H24O3Si (5) or C12H24OSi2 (6)) was added, it was possible to convert 5 and 6 into the desired silicon containing alpha,omega-diooelefins quantitatively. (C) 2000 Elsevier Science S.A. All rights reserved.