New Co (II), Cu (II) and Zn (II) complexes of a Schiff base have been prepared and characterized by elemental analyses, IR, and H-1-NMR spectroscopy, thermogravimetric analysis, conductometric and magnetic measurements. The results suggested that the Schiff base is a bivalent anion with tridentate ONS donors derived from the phenolic oxygen, azomethine nitrogen and thiophenolic sulfur. The formulae were found to be [ML.H2O] and [ML2] for the 1 : I and 1 : 2 non-electrolytic complexes, respectively. The thermal decomposition of the complexes follows first order kinetics and the thermodynamic parameters of the decomposition were calculated.