Department of Chemistry, St. Pius X College, Rajapuram, Kasaragod-671 532 Department of Studies in Chemistry, Mangalore University, Mangalagangothri-574 199 Manuscript received 17 March 1997, revised 28 July 1997, accepted 29 August 1997 This paper illustrates the thermal behavior of 4-amino-3-mercapto-6-methyl-1,2,4-triazin(4H)-5-one (AMMT) complexes of RuII and PtIV. The kinetic parameters are evaluated from the major decomposition part by a computed least-squares method using general (G), Coats-Redfern (CR), Freeman-Carroll (FC) and Horowitz-Metzger (HM) equations. The activation energy (E), Arrhenius parameter (A) and activation entropy are calculated. The values of kinetic parameters obtained by these different methods agree well. The thermal decomposition of these complexes follow first order kinetics. The negative values of entropy of the complexes indicate that the activated complex has more ordered structure than the reactants.