From an aqueous-ethanolic solution of CuCl2, 5,5′-dmbpy (5,5′-dmbpy=5,5′-dimethyl-2,2′-bipyridine) and K2 [Ni(CN)4], a novel Cu/Ni heterobimetallic complex [Ni(5,5′-dmbpy)3]2[NiCu2(CN)8]·6H2Owas isolated and characterized. Its ionic crystal structure contains the unprecedented Cu(I)/Ni(II,D4h) complex anion [Cu2Ni(CN)8]4−, along with the rarely structurally characterized [Ni(5,5′-dmbpy)3]2+ complex cation and water solvate molecules. The anions and water molecules are linked by hydrogen bonds, yielding a 1D supramolecular structure. Magnetic measurements performed down to 1.8 K revealed a Curie behavior between 15 and 300 K, while a small zero field splitting effect can be seen below 15 K.