Homo- and heteroleptic palladium(II) complexes of thiazoline derived ligand were synthesized and their catalytic application was reported. The reactions of [1-(C3H4NS)-2-OH-C6H4] (2) with PdCl2 and [(1-(CH3)2NCH2C6H4)PdCl]2 in 2:1 molar ratios afforded the homoleptic palladium complex, [Pd{κ1 2, κ1 2-N,O-(1-(C3H4NS)-2-O-C6H4)2}] (3) and the heteroleptic palladium complex [{κ1 2-N,O-(1-(C3H4NS)-2-O-C6H4)}Pd{(κ2 2-N,C-(1-(CH3)2NCH2C6H4)}] (4) respectively. Equimolar reactions of 2 with PdCl2 and 8-quinolinol or 2-methyl-8-quinolinol under reflux condition produced the heteroleptic palladium complexes [{κ1 2-N,O-(1-(C3H4NS)-2-O-C6H4)}Pd{(κ2 2-N,O-(8-O-C9H6-1-N)}] (5) or [{κ1 2-N,O-(1-(C3H4NS)-2-O-C6H4)}Pd{(κ2 2-N,O-(8-O-2-CH3-C9H5-1-N)}] (6) in good yields. The molecular structures of ligand 2 and palladium complexes 3–6 were confirmed through multinuclear NMR spectroscopic techniques and further the crystal structure for palladium complexes 3 and 4 were established. Under the optimized reaction condition, the heteroleptic palladium complex 4 display an excellent catalytic activity with a maximum turn over frequency of 49.5 h−1 for the conversion of bi-aryls from aryl halides and unactivated phenylhydrazine. The energies, activation barriers and transition state structures of reaction involved in the catalytic cycle were assessed by utilizing quantum chemical method to confirm Csp 2-Csp 2 bond formation reaction catalyzed by heteroleptic palladium complex 4. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim