In the crystal struture of the title compound, C16H14O6·C3H7NO, the two crystallographically independent benzene rings are coplanar [dihedral angle = 1.00 (2)°]. The crystal structure is stabilized by O—H⋯O hydrogen bonds between the diacid and the solvate dimethylformamide molecule, resulting in the formation of a zigzag chain structure extending parallel to [001].