Together, ortho (o)-phenyldiamine and para (p)-hydroxy benzaldehyde generate a Schiff base (SB). In order to make transition metal complexes of Ni2+, Cu2+, Co2+ and Cd2+ ions, this Schiff base (SB) was employed as a ligand of choice. The generated transition metal complexes' chemical structure is examined using a variety of physical methods, such as fundamental analysis, conductivity (molar), susceptibility (magnetic), spectroscopy (IR), and electronic spin spectroscopy. According to the elemental data analysis, a 1:2 [M:2L] complex of the formula, is produced ( M2+ = Ni2+, Cu2+, Co2+ and Cd2+ ions and L= Schiff base). All of the complexes were shown to be electrolytic in nature, as demonstrated by the molar conductance (conductivity) experiment. The 1H NMR and infrared (IR) spectral studies were utilized to fix the Schiff base binding sites that the transition metal ions are attached to. The anticipated coordination geometry and magnetic characteristics, such as the magnet with paramagnetic or diamagentic of the complexes were validated by the magnetic susceptibility tests and electronic spectral data. While the Cd2+ ion creates tetrahedral structure with low spin, the Ni2+and Cu2+, Co2+ ions yield high spin tetrahedra geometry. Comparing the obtained results with common antibiotics as kanamycin and ampicillin, the Cu2+ and Ni2+complexes showed high activity, while the Co2+ and Cd2+ complexes showed week and occasionally moderate antimicrobial activity. The complex compounds of Schiff base showed more activity towards gram position and gram negative bacteria as compared to its Schiff base. This idea can be improved upon with more adjustments and used in the pharmaceutical or medical industries.