N'-(2,5-Dihydroxy-benzyl-idene)benzene-sulfonohydrazide

In the title compound, C(13)H(12)N(2)O(4)S, the dihedral angle between the two aromatic rings is 89.5 (1)°. In the crystal structure, mol-ecules are linked by O-H⋯O(hydr-oxy) and N-H⋯O(sulfon-yl) hydrogen bonds, forming a ribbon that propagates along the b axis; there is also an intra-molecular O-H⋯N hydrogen bond.