Abstract: The hydrosilylation of 3-allylbenzo-15-crown-5 with trichlorosilane was carried out in the presence of platinum-octanol complex as catalyst. After treating the adduct with excess methylmagnesium bromide, 3-(γ-trimethylsilylpropyl)benzo-15-C-5 was obtained. Four silicons with pendant crown ether units and two silica-bound crown ethers were synthesized via hydrosilylation of alkyl chlorosilanes. Their thermostabllity and PTC activity were also investigated.