Dimethyl sulfoxide (DMSO) is a sulfur-containing organic compound with the molecular formula of C₂H₆SO.

t is a colorless and odorless transparent liquid at normal temperature and a hygroscopic combustible liquid. It has the characteristics of high polarity, high boiling point, good thermal stability, aprotic and water miscible, and can be dissolved in most organic substances such as ethanol, propanol, benzene and chloroform. It is known as "universal solvent". Heating in the presence of acid will produce a small amount of methyl mercaptan, formaldehyde, dimethyl sulfur, methanesulfonic acid and other compounds. It decomposes at high temperature, reacts violently with chlorine, and burns in the air to emit a light blue flame. It can be used as organic solvent, reaction medium and organic synthesis intermediate.