The first silylyne complex of a metal beyond group 6, [Cp*((Pr3P)-Pr-i)(H)Os Si(Trip)][HB(C6F5)(3)], was prepared by a new synthetic route involving hydride abstraction from silicon. NMR and DFT computations support the presence of a silylyne ligand, and NBO and ETS-NOCV analysis revealed the nature of this Os-Si interaction as a triple bond consisting of a covalent sigma bond and two strong pi back-donations. The discovery of this complex allowed observations of the first cycloadditions involving a silylyne complex, and terminal alkynes are shown to react via C-H bond additions across the Os Si bond.