Different types of Cu-based nanoparticles, namely Cu2O, Cu and CuO were homogeneously dispersed on cubic ordered mesoporous carbon CMK-8 (denoted as Cu2O@CMK-8, Cu@CMK-8 and CuO@CMK-8, respectively) and their performances for catalytic reduction of 4-nitrophenol (4-NP) were comparatively studied. The average particle size of Cu2O, Cu, and CuO nanoparticles confined in CMK-8 were estimated to be 4.0, 8.1, and 4.3 nm, respectively. In comparison to Cu@CMK-8 and CuO@CMK-8, the Cu2O@CMK-8 nanocomposite exhibits an outstanding rate constant of 2.21 x 10(-2) s(-1) and an exceptionally high activity parameter of 203 s(-1) gCu(-1) when the actual Cu loading is considered. The uniform particle size distribution along with high BET surface area and the ability to generate highly active nascent Cu(0) nanoparticles during the catalytic process activate both the 4-NP and BH4- to be efficiently adsorbed on the active sites of Cu2O@CMK-8. It is found that the catalytic properties of these Cu-based CMK-8 nanocomposites strongly depend on the state of Cu and their particle size. Furthermore, Cu2O@CMK-8 is highly reusable for five successive cycles without significant degradation of its activity. (C) 2017 Elsevier B.V. All rights reserved.