The acyclic diene metathesis (ADMET) copolymerization of divinyltetraethoxydisiloxane with 1,9-decadiene, catalyzed by RuCl2(=CHPh)(PCy3)(2), is the first example of a siloxylene-vinylene-alkenylene copolymer reported in the literature. This copolymer was isolated and characterized by H-1, and C-13 NMR spectroscopy and GPC analysis (M-n = 18 000, PDl = 2.9). (C) 2002 Elsevier Science B.V. All rights reserved.