Hydroxy-1,4-benzoquinone, also called hydroxy-para-benzoquinone, is an organic compound with formula C6H4O3, formally derived from 1,4-Benzoquinone by replacing one hydrogen atom with a hydroxyl (OH) group.

The compound is often called 2-hydroxy-1,4-benzoquinone, but the "2-" prefix is superfluous since there is no other hydroxy derivative of 1,4-benzoquinone.

It is formed by the reaction of 1,4-benzoquinone with hydrogen peroxide and is a byproduct of the metabolism of phenols, such as 1,2,4-benzenetriol.

[1] The enzyme 1,2,4-benzenetriol dehydrogenase catalyzes the conversion of 1,2,4-benzenetriol to 2-hydroxy-1,4-benzoquinone, and the enzyme hydroxybenzoquinone reductase catalyzes the reverse reaction.

It tends to dimerize spontaneously by peroxo bridges.