Abstract: | In the title compound, C18H15OP·C7H5ClO2, the triphenylphosphine oxide molecule forms a single directed hydrogen bond with the 3‐chlorobenzoic acid molecule, with an O⃛O=P distance of 2.607 (2) Å. The C—Cl and C=O bonds adopt a cisoid conformation in the 3‐chlorobenzoic acid molecule. |