In the title compound, C16H14O4, the benzene rings are inclined to one another by 4.91 (7)°. The conformation about the C=O and C=C bonds istransandcis, respectively. In the crystal, molecules are linked by O—H...O hydrogen bonds, forming inversion dimers with anR22(14) ring motif. The dimers are linkedviaO—H...O and C—H...O hydrogen bonds, forming undulating two-dimensional networks lying parallel to (10-1). These networks are linked by further C—H...O hydrogen bonds, forming a three-dimensional structure.