Abstract Methods are discussed for the synthesis of poly(triorganovinylsilanes), viz. poly(vinyltrimethylsilane) and poly(vinylallyldimethylsilane), silane-siloxane and silane-butadiene blockcopolymers. Mass-transfer properties (permeability, diffusion and solubility coefficients; P, D and σ respectively) are presented for poly(vinyltrimethylsilane), vinylsilane copolymers and poly(trimethylsilylpropyne). The detailed studies on mass-transfer parameters of these and some other polymers revealed that those with pendent organosilicon groups are characterized by higher P, D, and a values compared with the values for other glassy and many rubbery polymers. Spin probe and positron annihilation studies on poly(vinyltrimethylsilane) point to high free volume in the polymer, due apparently to the presence of bulky trimethylsilyl substituents.