The Schiff base ligands 1-(2-furanyl) ethanone isonicotinoylhydrazone (L5H), 1-(2-thienyl)ethanone isonicotinoylhydrazone (L6H), 1-(2- pyridyl)ethanone isonicotinoylhydrazone (L7H), 1-(2-naphthyl)ethanone isonicotinoylhydrazone (L8H), were prepared by the condensation reaction of isonicotinic acid hydrazide with corresponding ethanons in 1:1 molar ratio, respectively, in ethanol under microwave exposure. The Mn (II) complexes have been prepared by mixing MnCl2.4H2O in 1:1 and 1:2 molar ratios with monofunctional bidentate ligands. The structure of the ligands and their transition metal complexes were confirmed by the elemental analysis, molecular weight determinations, IR, electronic and EPR spectral studies. On the basis of these studies it is clear that the ligands coordinated to the metal atom in a monobasic bidentate mode, by O∩N donor system. Thus a tetrahedral environment around the Mn(II) ion has been proposed. The antimicrobial activity of Schiff base ligands and their respective Mn(II) complexes were tested against some of pathogenic bacterial and fungal strains. The results indicated that the complexes showed higher activity than the parent ligands.