Copper coordination compounds play an important role in the active sites of a large number of metallo-proteins in biological systems and have high potential application for numerous catalytic processes in living organisms that involve electron transfer reactions or activation of some antitumor substances [1]. The widest studied thiosemicarbazones are the sulphur and nitrogen-based ligands. Additionally, these molecules can also form multiple hydrogen bonds through their (thio) amide and N3 nitrogen that ensure a strong interaction with the receptors [2-3]. The thiosemicarbazones side chain located at position α to the heterocyclic nitrogen, through conjugated NNS tridentate ligand system, is essential for anticancer activity. In metal complexes, thiosemicarbazones can act as a tridentate ligand were the donor atoms are the thione/thiol sulfur atom and azomethine nitrogen atom. The possible ligation in copper(II) complexes with thiosemicarbazones derivatives of the formylquinoline can be either as a neutral molecule or as a monobasic anion due to loss of hydrogen from azomethine nitrogen atom [4]. In this work, we present six ligands derivatives of the 8-formylquinoline thiosemicarbazone. A new series of Cu(II) complexes with these ligands have been synthesized and characterized by CHNS elemental analysis, 1H-NMR, 13C-NMR and IR spectroscopy and structurally analyzed by X-ray single-crystal diffraction. The antibacterial activities of ligands and complexes are tested against different bacteria. A comparison of the antimicrobial activity of the complexes and that of the free ligands revealed that the coordination of Cu(II) improved the biologic activity against different bacteria. 1Padhye, S. and Kauffman, G.B., Coordination Chemistry Reviews, 1985, 63, 127-160. 2Beraldo, H.; Gambino, D. Mini-Rev. Med. Chem. 2004, 4, 31–39. 3Alonso R, Bermejo E, Carballo R, Castineiras A, J. Mol. Struct. 2002; 606, 155-73. 4M. D. Revenko, P. N. Bourosh, E. F. Stratulat, M. Gdaniec, Ya. Lipkowski, I. D. Korzha, and Yu. A. Simonov. Russian Journal of Inorganic Chemistry, 2010, 55, No. 9, 1387–1397.