Two new complexes [Cu(Phen) 2 (H 2 O)](Hba) 2 •3H 2 O (1) and [Ni(Phen) 3 ](Htba) 2 ]•Phen•2H 2 O (2) (Phen ¼ 1,10-phenanthroline, Hba À ¼ barbiturate ion, Htba À ¼ thiobarbiturate ion) have been synthesized and characterized by elemental analysis, single-crystal and powder XRD, magnetic measurements, TG-DSC, FT-IR, and Vis absorption spectra. Complex 1 shows a distorted square pyramidal geometry around the copper (II) metal center. The coordination around the Ni atom is a distorted octahedron NiN 6 . The 3D and 2D supramolecular structures of 1 and 2 are formed respectively by intermolecular H-bonds. Two NeH/O hydrogen bonds in 1, and NeH/O, NeH/S hydrogen bonds in 2 form infinite chains. As a result of pep interactions, similar 4-membered zigzag chains in structures 1 and 2 respectively are formed.