The trihydroxybenzenes (or benzenetriols) are organic compounds with the formula C<sub>6</sub>H<sub>3</sub>(OH)<sub>3</sub>. Also classified as polyphenols, they feature three hydroxyl groups substituted onto a benzene ring. They are white solids with modest solubility in water.
The enzyme pyrogallol hydroxytransferase uses benzene-1,2,3,5-tetrol and benzene-1,2,3-triol (pyrogallol), whereas its two products are benzene-1,3,5-triol (phloroglucinol) and benzene-1,2,3,5-tetrol. This enzyme can be found in Pelobacter acidigallici.