The research includes the preparation of a new Schiff base(4-methyl-2-((2-phenyl hydrazineylidene)methyl)naphthalen-1-ol), which was subsequently, used to prepare a series of complexes using chlorides of Mn2+, Co2+, Cu2+, Cr3+, and Fe3+ ions. The synthesized compounds were characterized using various techniques such as elemental microanalysis (C.H.N), chloride content determination using Mohr’s method, FT-IR spectroscopy, UV-Visible, mass spectra, conductivity, DSC (Differential Scanning Calorimetry), and thermogravimetric analysis. Overall, the decay of the ligand and its metal complexes was recorded to determine their thermal stability and weight-loss profiles. The results indicated that ligand acts as a bidentate doner, coordinating with metal ions through the nitrogen atom of the azomethine group (N=C-CH3) and oxygen atom of the phenol group. Most of the complexes exhibited an octahedral geometry, except for copper complex which gave tetrahedral structure. Additionally, the antioxidant activity of the compounds was evaluated by assessing their free radical scavenging ability using ascorbic acid as the reference and DPPH as a free radical and measuring the IC50 values. The results were Ascorbic acid > Ligand > [Cu(L)(H2O)(Cl)] > [Fe(L)(H2O)2(Cl)2] > [Cr(L)(H2O)2(Cl)2] > [Co(L)(H2O)3(Cl)] > [Mn (L)(H2O)3(Cl)].