Acetonitrile is an organic molecule, often used as a solvent, with the chemical formula of CH₃CN. Also known as methyl cyanide, it is the simplest of the organic nitriles.

At normal temperatures, acetonitrile is a colorless liquid. Its molecular weight is 41.05, with a melting temperature of -45C and a boiling temperature of 81.6C. The four main producers of acetonitrile in the United States are: BP Chemicals, Dupont, J.T. Baker Chemical, and Sterling Chemicals. In 1992, 32.3 million pounds (14,700 t) of acetonitrile were produced in the U.S.

Its use is as an extraction solvent for butadiene. It is also used as a chemical intermediate in pesticide manufacturing, and as a general solvent for many compounds. It is also used as a starting material for producing compounds like acetophenone, thiamine, etc. Finally, it can be used in the production of acrylic fibers, perfumes, nitrile rubber, and ABS resins. Trends for acetonitrile generally follow those of acrylonitrile.

Acetonitrile is absorbed through oral, dermal, or inhalation exposure. It is metabolized into hydrogen cyanide and thiocyanate, which is a serious cause of health problems in humans. Acetonitrile liquid or vapor is an acute irritant, irritating the skin, eyes, and respiratory tract. At high doses, death can occur due to respiratory failure. Lower doses have symptoms similar to those of cyanide poisoning, including salivation, nausea, unconsciousness, convulsions, etc. Prolonged exposure to acetonitrile has possible symptoms, including anorexia, headaches, and other related symptoms. There is no information (currently) about the possibility of acetonitrile's carcinogenicity.