This paper presents the catalytic effect of Al/(CUO) nanothermite on thermal decomposition of RDX. Currently, synthesizing a green alternative for primary explosives has become a new challenge for researchers. Therefore, feasibility of nanothermite-based nanocomposite Al/(CUO)/RDX was studied in this work. To this end, the (CUO) nanoparticles (NPs) are synthesized by the sol-gel method and applied as a nanocatalyst in thermal decomposition of RDX, as well as an oxidant in an Al-based nanothermite. The (CUO) NPs were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), and Brunauer-Emmett-Teller (BET). The XRD, FE-SEM, HRTEM, and BET images showed the excellent synthesis of spherical morphology of the (CUO) NPs with a mean size of 40.50 nm, and with surface area of approximately 25.98 m2/g. The reactivity was evaluated using thermogravimetry (TG) and differential scanning calorimetry (DSC), and the results show that the heat release of Al/(CUO)/RDX nanocomposite is 0.42 kJ/g more than that of pure RDX. It is shown, for the first time, that the electron transfer from Al/(CUO) nanothermite to –N–NO2 of RDX might play an important role in determining the catalytic properties of Al/(CUO) nanothermite.