The thermal stability of five commercial ion-exchange resin catalysts was studied by means of thermal gravimetric analysis(TGA) at elevated temperatures of up to 600℃and isothermal temperatures in the range of 150℃and 200℃.Resin samples with different initial water contents were also investigated.The study indicated that TGA,as a complementary evaluating method for the plug flow reactor system approach,could be used as a fast analyzing means for study on the thermal stability of ion-exchange resin catalysts.The stoichiometric calculation of the isothermally treated resin catalysts based on the FTIR analysis and acid capacity confirmed that the weight loss of the resins at 150℃and 200℃was caused by the desulfonation process and that desulfonation occurred mainly at the para-position of the benzene ring in the resins.H~+ ions and moisture played an important role in the desulfonation process. The thermal stability of five commercial ion-exchange resins was studied by means of thermal gravimetric analysis (TGA) at elevated temperatures of up to 600 ° C and isothermal temperatures in the range of 150 ° C and 200 ° C. Resin samples with different initial water contents were also investigated. The study indicated that TGA, as a complementary evaluating method for the plug flow reactor system approach, could be used as a fast analyzing means for study on the thermal stability of ion-exchange resin catalysts.The stoichiometric calculation of the isothermally treated resin catalysts based on the FTIR analysis and acid capacity confirmed that the weight loss of the resins at 150 ° C and 200 ° C was caused by the desulfonation process and that desulfonation occurred primarily at the para-position of the benzene ring in the resins. H ~ + ions and moisture played an important role in the desulfonation process.