1,2-Dibromoethylene, also known as 1,2-dibromoethene and acetylene dibromide, is a dihalogenated unsaturated compound with one bromine on each of the two carbon atoms.

There are two isomers of this compound, cis and trans.

1,2-Dibromoethylene can be synthesized by halogenation of acetylene (C2H2) with bromine (Br2).

[1] In order to prevent the formation of tetrahalogenated compounds, acetylene is used in excess, with Br2 as the limiting reagent.

Alternately, halogenation of this kind could also be achieved through the use of two equivalents of N-bromosuccinimide and lithium bromide (LiBr).