The title compound, C16H14O6, was recrystallized under solvothermal conditions. The molecules are located on inversion centres, with one complete molecule generated from the asymmetric unit by inversion. There are intramolecular O—H⋯O hydrogen bonds involving the carboxylic acid group and the O atom of the adjacent methoxy group. In the crystal, molecules are linked via O—H⋯O hydrogen bonds, forming chains propagating along [100]. The chains are linked via C—H⋯O hydrogen bonds, forming sheets parallel to (001).