Bis(trimethylsilyl) sulfide is the chemical compound with the formula ((CH3)3Si)2S.

Often abbreviated (tms)2S, this colourless, vile-smelling liquid is a useful aprotic source of "S2−" in chemical synthesis.

[3] The reagent is prepared by treating trimethylsilyl chloride with anhydrous sodium sulfide:[4] ((CH3)3Si)2S must be protected from air because it hydrolyzes readily: Bis(trimethylsilyl)sulfide is a reagent for the conversion of metal oxides and chlorides into the corresponding sulfides.

[5] This transformation exploits the affinity of silicon(IV) for oxygen and halides.

An idealized reaction is: In a similar way, it has been used in the conversion of aldehydes and ketones to the corresponding thiones.