Abstract: Novel transition metal(II) complexes, [M(L₁)₂Cl₂] and [M(L₂)₂Cl₂], were synthesized from the reaction of MCl₂.nH₂O (M = Co, Ni, Cu) with (Z)-1-(1-(1H-indol-3-yl)ethylideneamino)quinolin-2(1H)-one (L₁) or (E)-1-(2-hydroxybenzylideneamino)quinolin-2(1H)-one (L₂). The ligands were obtained from coumarin. N-amino quinoline-2-one (2) has been synthesized by the reflux of coumarin (1) with hydrazine hydrate in ethanol for 12 hr. The azomethines (L₁, L₂) were prepared from the corresponding aryl aldehydes. The synthesized compounds were and characterized by element chemical analysis, molar conductance, magnetic susceptibility measurements, and spectral (electronic, and FT-IR) studies. The IR spectral data suggest the involvement of sulphur and azomethane nitrogen in coordination to the central metal ion. On the basis of spectral studies, an octahedral geometry has been assigned for all complexes. The free ligands and its metal complexes have been tested in vitro against a number of microorganisms in order to assess their antimicrobial properties.