The title cocrystal, C18H15OP·C6H6O2, belongs to a series of mol­ecular systems based on triphenyl­phosphine P-oxide. The O atom of the oxide group acts as an acceptor for hydrogen bonds from OH groups of two hydro­quinone mol­ecules which lie on inversion centres [O⋯O = 2.7451 (17) and 2.681 (2) Å]. The crystal structure is stabilized by weak C—H⋯O hydrogen bonds, forming a C21(8) chain which runs parallel to the [100] direction.