Nickel(II) complexes containing thiosemicarbazone ligands [Ni(L)₂] (1-3) (L = 9,10-phenanthrenequinonethiosemicarbazone (HL₁), 9,10-phenanthrenequinone-N-methylthio semicarbazone (HL₂) and 9, 10-phenanthrenequinone-N-phenylthiosemicarbazone (HL₃)) have been synthesized and characterized by elemental analysis and spectroscopic (IR, UV-Vis, ¹H, ¹³C-NMR and ESI mass) methods. The molecular structures of complexes 1 and 2 were identified by means of single-crystal X-ray diffraction analysis. The analysis revealed that the complexes possess a distorted octahedral geometry with the ligand coordinating in a uni-negative tridentate ONS fashion. The catalytic activity of complexes towards some C–C coupling reactions (viz., Kumada-Corriu, Suzuki-Miyaura and Sonogashira) has been examined. The complexes behave as efficient catalysts in the Kumada-Corriu and Sonogashira coupling reactions rather than Suzuki-Miyaura coupling.