1,2-Benzoquinone, also called ortho-benzoquinone or cyclohexa-3,5-diene-1,2-dione, is a ketone, with formula | C=6 | H=4 | O=2 . It is one of the two isomers of quinone, the other being 1,4-benzoquinone.

1,2-Benzoquinone is produced on oxidation of catechol exposed to air in aqueous solution or by ortho oxidation of a phenol. It is a precursor to melanin. It is a red substance soluble in water and insoluble in ethyl ether.