The elastomeric nanocomposites based on organomontmorillonite (OMMT) and styrene-(ethylene-butylene)- styrene (SEBS) thermoplastic elastomer were prepared by melt processing using maleic anhydride grafted SEBS (SEBS-g-MA) as compatibilizer. Thermo-oxidative decomposition behavior of the neat components and the nanocomposites were investigated using thermogravimertic analysis (TGA) in air atmosphere. The isoconversional method is employed to study the kinetics of thermo-oxidative degradation. The heating modes and the composition of nanocomposites were found to affect the kinetic parameters (E(a), lnA and n). The E(a) and lnA values of SEBS, OMMT, and their composites are much higher under dynamic heating than under isothermal heating. The reaction order (n) of OMMT was lower than those of SEBS and their composites. The obtained TG profiles and calculated kinetic parameters indicated that the incorporation of OMMT into SEBS significantly improved the thermal stability both under dynamic heating and under isothermal heating. The simultaneously obtained DSC data showed that the enthalpy of thermal decomposition decreased with OMMT loading. No significant change in the nonisothermal and isothermal stability of the nanocomposites with addition of SEBS-g-MA. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 120: 3337-3349, 2011