Bis(trimethylsilyl)acetylene (BTMSA) is an organosilicon compound with the formula Me3SiC≡CSiMe3 (Me = methyl).

It is a crystalline solid that melts slightly above room temperature and is soluble in organic solvents.

BTMSA is prepared by treating acetylene with butyllithium followed by addition of trimethylsilyl chloride (Me = CH3, Bu = C4H9):[1] BTMSA is used as a nucleophile in Friedel-Crafts type acylations and alkylations and a precursor to lithium trimethylsilylacetylide.

The TMS groups can be removed with tetra-n-butylammonium fluoride (TBAF) and replaced with protons.

[2] A key step in this synthesis was the formation of the steroidal skeleton, catalyzed by CpCo(CO)2.