Transition metal complexes of [N,O] donor ligands play an important role in many biological processes, such as bactericides, fungicides etc. The present monograph explains the synthesis and spectral characterization of some novel [N,O] donor ligands and their transition metal complexes. The ligands and their transition metal complexes are fully characterized on the basis of physical properties, elemental analysis, Infrared spectroscopy, Magnetic susceptibility, Ultraviolet spectroscopy, Atomic absorption spectroscopy, Thermo gravimetric analysis and 1H-13C NMR spectroscopy. Finally, the ligands and complexes are subjected to various microorganisms in order to establish the antibacterial activity,the results are quite promising.