The title compound, [Cu(2)(C(16)H(20)N(6)O(4))(NO(3))(2)(H(2)O)(4)]·3H(2)O, crystallizes with two dinuclear Cu(II) complex mol-ecules, each lying on an inversion center, and six solvent water mol-ecules per unit cell. The central 1,6-diazecine ring adopts the common chair conformation invariably found in the family of complexes bearing such ligands. The Cu(II) atoms have an octa-hedral geometry, with a very strong tetra-gonal distortion due to the Jahn-Teller effect. Axial sites are occupied by a nitrate ion and a water mol-ecule. The Cu⋯Cu separations [7.3580 (9) and 7.3341 (9) Å] are compatible with a potential catecholase activity. Neighboring mol-ecules in the crystal structure are connected via O-H⋯O hydrogen bonds formed by water mol-ecules and carboxyl-ate O atoms. N-H⋯O hydrogen bonds are also present.