A systematic study of the reduction behavior of various types of uniform Cu₂O nanocrystals reveals that the surface blocking effect exerted by the capping ligand on the reduction behavior of the Cu₂O nanocrystals depends not only on the type of capping ligand but also on the reactant and that coupling between adjacent crystal planes occurs for Cu₂O nanocrystals exposing two types of crystal planes during the reduction reactions and exerts great influence on the reduction kinetics of the involved crystal planes.