The hydrosilylation Of C-60 with 2,4,6,8-tetra-methylcylotetrasiloxane in the presence of platinum/carbon catalyst produced the cationically polymerizable (C(60)Hsi-MeO)(4) along with [(C60HSiMeO)(3)SiMeO](2)C60H2 and a polymer consisting of C-60 and (SiMeO)(4) units. The synthesis and characterization of this first polymerizable tetracyclo-siloxane ring system containing 1260 as a monoadduct substituent are also reported.