Benzoquinone (C₆H₄O₂) is a quinone with a single benzene ring. There are 2 (out of 3 hypothetical) benzoquinones:

• 1,4-Benzoquinone, most commonly, right image (also para-benzoquinone, p-benzoquinone, para-quinone, or just quinone)
• 1,2-Benzoquinone, less commonly, left image (also ortho-benzoquinone, o-benzoquinone, ortho-quinone)

• 1,3-benzoquinone "does not exist, because its structure would be nonplanar and highly strained",^[1] though derivatives are known.

An alkylated p-benzoquinone has been found in the rhizomes of Iris kemaonensis.^[2]