cis-3-Hexene is a symmetrical cis-disubstituted alkene that can be prepared by the hydroboration of 3-hexyne followed by protonolysis. The gas-phase study of its molecular structure by electron diffraction combined with molecular mechanical calculations reveals the presence of the (+ac, +ac) and the (-ac, +ac) forms. cis-3-Hexene undergoes epoxidation with dimethyldioxirane to form the corresponding epoxide.