The new bidentate Schiff base ligand (E)-N-(4-hydroxy-3-(1-(2-isonicotinoylhydrazono)ethyl)phenyl)acetamide (LH) and its Cu(II), Co(II), Th(IV) and Zr(IV) complexes have been synthesized by the conventional method. Compounds have been characterized by elemental analysis, IR, FAB-Mass, molar conductivities, magnetic measurements, electronic spectra, ESR and thermal analysis. Analytical data suggested 1:2 (metal: ligand) mole ratio for all the complexes. The low molar conductance values of the metal complexes in DMSO reveal their non-electrolytic nature. From the observed data of magnetic moment and electronic spectra, the six coordinated structures for all the complexes, have been proposed. The thermodynamic analysis shows that the complexes lose hydrated and/or coordinated water molecules in the first step; followed by decomposition of ligand moiety in the further steps leading to formation of stable oxide. The antibacterial screening results also indicate that the metal complexes are good antibacterial agents as compared to the Schiff base.