New complexes, [Fe(L)Cl], [Ni(L)], and [Zn(L)C2H5OH] (1-3), were synthesized by template reaction of 2-hydroxy-acetophenone-S-methyl-thiosemicarbazone with 2-hydroxy-benzaldehyde. The compounds were characterized by elemental analysis, magnetic measurements, FT-IR, H-1 NMR, UV-visible, and ESI-MS spectra. In these complexes, the ligand is coordinated to the metal ion as dinegatively charged tetradentate chelating agents via the N2O2 donor set. The iron(III) and zinc(II) complexes exhibit square pyramidal geometry whereas the nickel(II) complex has a square planar geometry. The crystal structure of 1, determined by X-ray diffraction method, indicates that 1 crystallizes in the monoclinic space group P21/c with Z=4. Thermal decompositions of the compounds have been investigated using TGA in air.