The synthesis, crystal structure, and characterization of a silicon-silicon triply bonded species, disilyne with two bis[bis(trimethylsilyl)methyl]isopropylsilyl substituents, are described. The nature of the sp-hybridized silicon atoms is discussed from the viewpoint of spectroscopic results and theoretical calculations. The reactivity of the disilyne with alkali metals, t BuLi, and π-bonded compounds such as cis-and trans-2-butenes and phenylacetylene is also described.