The 2:1 complex of 4-amino­benzoic acid and 4,4′-bipyridyl N,N′-dioxide

The co-crystal C10H8N2O2·2C7H7NO2 owes its formation to an intermolecular hydrogen bond between the O—H and N—O groups; the O⋯O distance is 2.5796 (17) A. The dihedral angle between the planes of the pyridyl N-oxide and amino­benzoic rings of the complex is 10.2 (1)°. An additional intermolecular C—H⋯O hydrogen bond is formed, giving rise to an eight-membered ring within the asymmetric unit. The structure is centrosymmetric about the mid-point of the bond joining the two pyridine rings. The crystal structure exhibits overlap between the aromatic rings of the mol­ecules in the [\overline 110] direction.