In the title compound, [Cu(2)Cl(2)(NO(3))(2)(C(12)H(8)N(2)O(4))(2)(H(2)O)(2)], which consists of a chloride-bridged Cu(II) dimer, the Cu atom is in a distorted octa-hedral environment defined by two N atoms from the 2,2'-bipyridine-4,4'-dicarboxylic acid ligand (H(2)bpdca), two bridging chlorido ligands, and two O atoms from an equatorial water mol-ecule and an axial nitrate anion, respectively. The two halves of the dimeric unit are related by an inversion centre at the midpoint between the two Cu atoms. Both carboxylic acid groups in the H(2)bpdca ligand remain protonated, as confirmed by the two sets of C-O bond lengths. The dinuclear mol-ecules are linked into a three-dimensional network via inter-molecular hydrogen bonds.