A series of difunctional silicon-containing monomers were prepared with a novel method consisting of the monohydrosilation of an alpha,omega-difunctional Si-H-terminated siloxane with a vinyl-functional epoxide or oxetane followed by the dehydrodimerization of the resulting Si-H-functional intermediate. This method used simple, readily available starting materials and could be conducted as a streamlined one-pot, two-step synthesis. This novel method was also applied to the synthesis of several epoxy-silicone oligomers. The reactivities of these new monomers and oligomers were examined with Fourier transform real-time infrared spectroscopy and optical pyrometry. Those monomers containing epoxycyclohexyl groups displayed excellent reactivity in cationic ring-opening polymerization in the presence of lipophilic onium salt photoinitiators. (C) 2003 Wiley Periodicals, Inc.