Tetramethylethylene is a hydrocarbon with the formula Me2C=CMe2 (Me = methyl).

A colorless liquid, it is the simplest tetrasubstituted alkene.

It can be prepared by base-catalyzed isomerization of 2,3-dimethyl-1-butene.

[2] Another route involves direct dimerization of propylene.

[4] Tetramethylethylene forms metal-alkene complexes with low-valent metals and reacts with diborane to give the monoalkyborane known as thexylborane.