Hexachlorodisilane is the inorganic compound with the chemical formula Si₂Cl₆. It is a colourless liquid that fumes in moist air. It has specialty applications in as a reagent and as a volatile precursor to silicon metal.

The molecule adopts a structure like ethane, with a single Si-Si bond length of 233 pm.

Hexachlorodisilane is produced in the chlorination of silicides such as e.g. calcium silicide. Idealized syntheses are as follows:

Hexachlorodisilane is stable under air or nitrogen at temperatures of at least up to 400°C for several hours, but decomposes to dodecachloroneopentasilane and silicon tetrachloride in presence of Lewis bases even at room temperature.

This conversion is useful in making silicon-based components of use in semiconducting devices including photovoltaic cells.

The compound is also useful reagent for the deoxygenation reactions, such as this general process involving a phosphine oxide: