The two ligands (E)-3-(2-(5-(2-(5-(2-hydroxyphenyl)-1,3,4-oxadiazol-2-yl)hydrazineyl)-1,3,4-thiadiazol-2-yl) hydrazineylidene)indolin-2-one (L1) ,(E)-5-(5-(2-(5-(2-((1H-pyrrol-2-yl)methylene hydrazinyl)-1,3,4-thiadiazol-2-yl)hydrazinyl)- 1,3,4-oxadiazol-2-y1) benzene-1,2,3-triol (L2) and their Fe(III) and Ni(II) complexes were synthesized by addition and elimination reactions .The ligands and their complexes characterized by spectroscopic methods (FTIR , 1H-NMR , MS ). The ligand acts as a bidentate ligand coordinating through the nitrogen atom of the oxadiazole ring and the nitrogen atom of amino group. This view is further supported by the appearance of a band corresponding to the metal-nitrogen and vibration at 454–688 cm–1 and 314-466 cm-1 in the complexes respectively. The magnetic studies suggest a octahedral and square planar geometry of the complexes. The complex of Fe (III) have shown octahedral geometry, the complex of Ni (II) has shown square planar geometry with prepared ligands. HOMO-LUMO molecular orbitals analysis of these ligands (L1,L2) and some quantum chemical parameters derived from frontier molecular orbitals were studied. The new ligands and their complexes has shown moderate to good activity against three type fungi .