Polybutadienes having a variety of different microstructures have been hydrosilated using HSiMexCl3-x, x=0-2 in the presence of H2[PtCl6]. High conversions of double bonds pendant from the main chain are observed but hydrosilation also occurs on the backbone of the polymer especially if there is a high percentage of backbone double bonds. This backbone hydrosilation is accompanied by double-bond migration along the polymer backbone to give conjugated diene units within the polymer backbone. These polymers have been further functionalised by reactions with alcohols [EtOH, EtO(CH2CH2O)2H, 4-hydroxybiphenyl or MeO(CH2CH2O)nH (M(n) = 500 or 750)] in the presence of Et3N or by alkylation, e.g. with 2-lithiomethylpyridine or with 6-lithio-2,2'-bipyridine. Polymers containing -SiMex(OR)3-x,x = 2 or 0, R = EtO(CH2CH2O)2H or MeO(CH2CH2O)nH (M(n) = 500 or 750) have been shown to form polymer electrolytes, in some cases with room-temperature conductivities as high as 2.5 x 10(-5) S cm-1. Sequential hydrosilation and epoxidation reactions have been carried out to give polymers in which the pendant double bonds have been hydrosilated and the backbone double bonds have been epoxidised.