Divalent metal chelates of 8-mercaptoquinoline (8-MQ) were prepared with copper, nickel, cobalt, zinc, lead, iron, cadmium, and mercury. The thermogravimetry and differential thermal analysis of each of the chelates were studied and a thermal stability order of Cd>Co>Ni>Zn>Pb>Hg>Fe>Cu was obtained. This order is compared with the order obtained with 8-hydroxyquinoline (8-HQ) chelates and the relative thermal stability temperatures of the chelate series are discussed in terms of ligand differences.