Four new Ni(II) complexes of the general formula [Ni(PPh 3 )(L)] (L=dibasic tridentate ligand derived from 4-diethylamino-salicylaldehyde and thiosemicarbazide or 4-N-substituted thiosemicarbazide) have been reported. The new complexes have been synthesized and characterized by analytical and spectroscopic (IR, electronic, 1 H NMR and 31 P NMR) techniques. Molecular structure of one of the complexes has been determined by X-ray crystallography. The complex, [Ni(PPh 3 )(L4)] (H 2 L4=thiosemicarbazone prepared from 4-diethylamino-salicylaldehyde and 4-phenylthiosemicarbazide) crystallized in monoclinic space group with two molecules per unit cell and has the dimensions of a=13.232(6)Å, b=10.181(5)Å, c=13.574(7)Å, α=90°, β=98.483(2)° and γ=90°. Catalytic activity of the complexes has been explored for aryl–aryl coupling reaction.