In this study, polyhedral oligomeric silsesquioxane glycidylisobutyl-POSS was dispersed in an epoxy resin (DGEBA) using ultrasound, and the thermal degradation was investigated by the Flynn-Wall-Ozawa and Criado methods using thermogravimetric analysis. The TEM analysis indicated higher polyhedral oligomeric silsesquioxane (POSS) dispersion in spherical shape. The POSS dispersion was associated with the formation of micelles as a result of their hybrid character. The addition of POSS did not change the degradation of the resin until similar to 380 A degrees C, and above this temperature, increase in the thermal stability was observed. The kinetic results revealed that the addition of POSS decreased E (a) values primarily to 10 % POSS and did not affect the mechanism of degradation for all contents. The reduction in E (a) was associated with the easier breaking of bonds at the interface of the DGEBA/POSS nanocomposite. The thermodynamic parameters suggested an increased "degree of arrangement" for the formation of an active complex during the degradation process and corroborate the lower E (a) values. The results suggest that the addition of POSS is able to cause an effect of thermal barrier at higher temperatures without affecting the homogeneity of the microstructure of the cured resin.