1,2-Dithiolane is an organosulfur compound with the formula S₂(CH₂)₃. It is also classified as a heterocycle derived from cyclopentane by replacing two methylene bridges (−CH₂− units) with a disulfide group. 1,3-Dithiolane is an isomer. The parent molecule is unimportant but substituted derivatives, especially lipoic acid and its derivatives, are often essential for life. Several occur naturally.

The parent 1,2-dithiolane is the disulfide derived from 1,3-propanedithiol. It is however unstable with respect to oligomerization. In general, 1,3-dithiols are superior reductants relative to monothiols.

Many substituted 1,2-dithiolates are found in nature. The most common is lipoic acid, a chiral dithiolane, which features a pentanoic acid substituent. It is essential for aerobic metabolism in mammals.

Some 1,2-dithiolane are found in some foods, such as asparagusic acid in asparagus. The 4-dimethylamino derivative nereistoxin was the inspiration for insecticides that act by blocking the nicotinic acetylcholine receptor.

Several alkyl-substituted 1,2-dithiolanes occur in the scent glands of skunks and related mammals. These include 3,3-dimethyl-, 3-propyl-, 3-ethyl-1,2-dithiolane, and others.

Many 1,2-dithiolanes can be oxidized to their S-oxides, which are chiral.