Acetone, propanone or dimethyl ketone, is an organic compound with the formula (CH3)2CO. It is the simplest and smallest ketone. It is a colourless, highly volatile and flammable liquid with a characteristic pungent odour.

Acetone is miscible with water and serves as an important organic solvent in its own right, in industry, home, and laboratory. About 6.7 million tonnes were produced worldwide in 2010, mainly for use as a solvent and production of methyl methacrylate (and from that PMMA) as well as bisphenol A. It is a common building block in organic chemistry.