In this study, epoxy nanocomposites containing 0.5, 1, 2, and 5% (m/m) of epoxycyclohexyl—POSS were prepared by mechanical mixture. The samples were characterized by gel content, thermogravimetric analysis (TGA), transmission electron microscopy, and scanning electron microscopy (SEM). TGA analysis was carried out at different heating rates (5, 10, 20, and 40°C min−1) aiming to evaluate the decomposition by Avrami, Flynn-Wall-Ozawa and Criado kinetic models. It was constated an increase in the gel fraction and dispersion of the nanocages only for the sample containing 5% POSS. The degradation study showed two distinct stages of weight loss and only for the first stage a shift in the temperature up POSS incorporation was observed. The Avrami kinetic parameters showed that the incorporation of POSS does not affect the degradation rate constant; however, there is an increase in the time required for the degradation reaction occurs. Also, it was observed an increase in the activation energy values for the sample containing 5% (m/m) of POSS. The degradation kinetic mechanisms in presence of POSS was changed from deceleratory mode (F1) for diffusion (Dn) in the range corresponded to the second stage of weight loss. SEM analysis showed that the morphology of the epoxy resin was modified by the POSS presence, and for 5% (m/m) of POSS was constated a more homogeneous morphology in relation to other samples. © 2012 Society of Plastics Engineers