The growth of Cu nanostructures on the hydrogen-terminated Si(111) surface was studied by scanning tunnelling microscopy (STM). On the hydrogen-terminated Si(111) surface, small Cu nanostructures scatter mainly on the terraces and a few structures along the steps and domain boundaries at a deposition temperature of ~310°C: the shape of the nanostructure is round or triangular, and the face is not clear. At ~340°C, the Cu nanostructures form preferentially at steps and domain boundaries of the substrate: the shape is triangular with truncated corners and the nanostructures have some facets. The top face has an inclination angle of ~6° and the side face has one of ~35°. On the top face, mono-atomic steps can be seen ~0.8 nm apart. From these results, it is concluded that the Cu nanostructure has a {554} facet on top and a {110} facet on the side. Copyright © 2003 John Wiley & Sons, Ltd.