In the title compound, C(15)H(10)O(5), the cyclo-penta-none (r.m.s. deviation = 0.049 Å) and oxolane (r.m.s. deviation = 0.048 Å) rings make a dihedral angle of 67.91 (4)°. An intra-molecular O-H⋯O hydrogen bond is observed. In the crystal, mol-ecules associate via O-H⋯O hydrogen bonds, forming a three-dimensional network.