Nanoscopic naked Cu/Pd alloy powders, particle size in 1-5 nm, were prepared by a cold alloying process. The formation of nanoscopic bimetallic hydroxide colloids as precursors of the nanoscopic alloy powders was studied by means of TEM, XRD, and a titration method. These bimetallic alloy powders have provided the first example of Cu-based catalysts with high activity, selectivity, and stability against air for the selective hydration of acrylonitrile to acrylamide.