In organic chemistry, a carbyne is a general term for any compound whose structure consists of an electrically neutral carbon atom connected by a single covalent bond and has three non-bonded electrons. The carbon atom has either one or three unpaired electrons, depending on its excitation state; making it a radical. The chemical formula can be written  or  (also written as ), or just CH.
Carbynes can be seen as derivatives of the simplest such compound, the methylidyne radical or unsubstituted carbyne  or , in which the functional group is a hydrogen atom.
Reported for the first time back in 1967 by Kasatochkin, carbyne is an infinite sp1 hybridized long linear chain of carbon, where each link is just a single carbon atom.