The title adduct, C(7)H(5)NO(4)·C(6)H(6)N(2)O(3), forms part of an ongoing study of the design of non-centrosymmetric systems based on 3-methy-4-nitro-pyridine 1-oxide. The components of the adduct are linked by inter-molecular O-H⋯O hydrogen bonds. The rings of the two components are nearly planar, with a dihedral angle of 11.9 (2)° between the planes. The supra-molecular structure shows that mol-ecules of the title complex are linked into sheets by a combination of strong O-H⋯O and weak C-H⋯O hydrogen bonds.