Novel series of Zn²⁺ and Pb²⁺ complexes derived from (Z)-2-(2-oxoindolin-3-ylidene)-N-phenylhydrazine-1-carbothioamide (H₂L¹) .IR,UV-vis, thermal (TGA DrTGA), and elemental (CHN) analyses were used to synthesize and analyze Zn²⁺ and Pb²⁺ complexes . DMol³ tool of the material studio program was utilized to obtain the optimized structures of the H₂L¹ ligand besides the prepared complexes. In both complexes, the ligand acts as a mononegative ONS tridentate. HOMO, LUMO, bond angles, bond lengths, and dipole moment were computed from the modeling studies to validate the geometry of the ligand beside that its studied chelates. They estimated the different kinetic and thermodynamic parameters using  Horowitz–Metzger and Coats–Redfern methods. The thermal analyses demonstrated both thermal decomposition occurred for the metal chelates and the kind of water molecules that are a part of them. Finally, the antioxidant and antimicrobial studies of the tested chelates were also evaluated.