Nanosized cuprous oxide filler particles (nCOP) with octahedral morphology were synthesized through hydrazine reduction method and were used to develop a novel nanocomposites based on epoxy resin. The morphology of epoxy-nCOP nanocomposites were analyzed using transmission electron microscopy and scanning electron microscopy. Differential scanning calorimetry analysis showed that the cure reaction rate of epoxy was found to increase with the addition of the nCOP and a plausible cure reaction mechanism was suggested. The activation energy required for the cure reaction reduced by 22% and 13% at the initial (E-1) and final stage (E-2) of the cure, respectively, by the incorporation of 3 phr nCOP. It was also shown that the kinetically controlled parts of reaction could be expressed well by Kamal's phenomenological model while end of curing process could not be completely expressed by this model as there it was diffusion controlled. The influence of nCOP on glass transition temperature (T-g), mechanical properties, and thermal stability of epoxy matrix was also investigated and the results showed that better characteristics were observed in presence of 3 phr nCOP loading. (C) 2015 Society of Plastics Engineers