In this study, copper oxide nanoparticles (CuO NPs) with mean particle size of 43-32nm were prepared by wet grinding of commercial micronized CuO powders in a high-energy wet ball-milling apparatus during 20 and 30h, respectively. X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM) analyses were used to characterize the structure, mean particle size and morphology of the resulting CuO NPs. The results confirmed that the CuO NPs obtained at different milling times consist of nanostructures with nearly spherical morphology and by increasing the milling time, smaller particle size was obtained. The catalytic activities of the synthesized CuO NPs on the thermal decomposition of ammonium perchlorate (AP) particles were examined through differential scanning calorimetry and thermogravimetry (DSC/TG) analyses. Evaluation of the experimental results illustrated that the surfaces of CuO NPs were effectively coated with AP particles and by adding 5%CuO NPs with 32nm, the thermal decomposition temperature of the treated particles reduced by 83.0 degrees C and the heat of decomposition reached 1553.7Jg(-1). Moreover, the kinetic and thermodynamic parameters of the thermal decomposition of pure and AP+5%CW30 nanocomposites have been investigated by using the Kissinger, Boswell and Ozawa methods.