Mononucleating complexes of isatin hydrazone sodium sulfonate ligand (HLn) with palladium (II) and cobalt (II) ions: The complexes were synthesized within 1:1 and 2:1 molar ratio of HLn with Pd 2+ and Co 2+ ion in PdLn and Co (Ln) 2 , respectively. The catalytic reactivity of both complexes was examined in the oxidation of sulfides (diphenyl sulfide, dps, and methylphenyl sulfide, mps) using hydrogen peroxide under aerobic conditions. Oxoproducts, dipheylsufoxide, dpo, and methyl phenyl sulfoxide, mpo, are the chemoselective products with detection of large amounts of the unselective further oxidation products of dioxoproducts (dipheylsufone, dpn, and methylphenyl sulfone, mpn). The homogenous catalyst of Co (Ln) 2 revealed more efficient action compared to that of PdLn depending on the high electrochemical reversible potential of the central metal ion in the catalytic reaction within the electron and/or oxygen transfer system. Exploring the importance of the M 2+ ion in the coordinated ligand, the bioreactivity of HLn, PdLn, and Co (Ln) 2 was illustrated within some commonly well-known bacteria and fungi strains. Additionally, they were involved as anticancer reagents against some human cancer cell lines in vitro. Both metal complexes presented high inhibited action versus the growth of the studied microorganism and cancer. The interaction effect of Pd 2+ and Co 2+ ions in their pincer complexes was tested with calf thymus DNA spectroscopically and via the viscosity changes.