Two new Schiff base ligands (L1, L2) derived from 2-pyridinecarboxaldehyde, benzaldehyde and 5-amino-1,3,4- thiadiazol-2-thiol have been synthesized. These ligands were treated with Cu (II) and Co (II) chloride with a metal : ligand ratio of 1:1 to afford the four new complexes [CuL1(H2O)2]Cl2, [CoL1Cl2], [CuL2(H2O)2]Cl2 and [CoL2(H2O)2]Cl2.These ligands and complexes have been characterized by IR, UV-visible absorption, molar conductance, magnetic measurements and atomic absorption . The data shows that the ligands are coordinate to metal atom by nitrogen to form square planer or tetrahedral complexes with Cu (II) and Co (II). The thermal properties were studied by TGA and DTG to discover the thermal stability of the complexes. The thermal behaviours of all the metal complexes were studied from room temperature to 700 oC in nitrogen atmosphere. The TGA and DTG studies of complexes expose that the decomposition continues in three steps.