The reaction of salicylaldehyde-4(N)-ethylthiosemicarbazone, [H-2-(Sal-etsc)] with [RuHCl(CO)(PPh3)(3)] afforded two isomeric ruthenium(II) carbonyl complexes namely [Ru(H-Sal-etsc)(CO)Cl(PPh3)(2)] (1) and [Ru(Sal-etsc)(CO)(PPh3)(2)]center dot Cl (2). The new complexes were characterized by various spectroscopic techniques (IR, Electronic, H-1 NMR and P-31 NMR) and X-ray crystallography. In this reaction, bidentate monobasic coordination with the formation of more strain NS four member chelate in (1) and tridentate monobasic coordination with the formation of ONS five and six member rings in (2) were observed. The binding interaction of complexes (1 and 2) to calf thymus(CT) DNA/Lysozyme has been explored. The cytotoxic nature of the complexes was evaluated on human lung/liver cancer cells, A549 and HepG2. (C) 2014 Elsevier B. V. All rights reserved.