Nanodiamond (ND) supported metal catalysts exhibit excellent catalytic activity. ND-doped Cu nanocrystal was prepared by reduction of CuSO 4 aqueous solution with 0.7-wt.% ND dispersed in. X-ray diffraction (XRD) result indicated introduction of ND caused a significant lattice contraction to Cu nanocrystals due to its smaller ionic radius. Transmission electron microscopy (TEM) results indicated that with addition of ND, the as-prepared ND/Cu particulates were thicker and more homogeneously dispersed than Cu. Free radicals of Cu as well as ND were detected for ND/Cu in electron paramagnetic resonance (EPR) spectra. Dopant of ND contributed to heterogeneous nucleation of Cu nanocrystal. Both Cu and ND/Cu nanoparticulates were strong catalysts for NH 4 ClO 4 (AP) and 1, 3, 5-trimethylene trinitramine (RDX) decomposition, moreover ND/Cu is more effective.