It consists of Cu+ cations and acetylide anions −C≡C−, with the triple bond between the two carbon atoms.

[5] Copper catalysts used in the chemical industry can also possess a degree of risk under certain conditions.

The copper is oxidized to Cu2+ and forms a blue soluble complex with the ammonia, leaving behind a black solid residue.

Samples that have been aged with exposure to air or to copper(II) ions liberate also higher polyynes H(−C≡C−)nH, with n from 2 to 6, when decomposed by hydrochloric acid.

Reactions between Cu+ and alkynes occur only if a terminal hydrogen is present (as it is slightly acidic in nature).