Thin conformal Cu 2 S overlayers are grown on Cu 2 O compact layers (CLs) and nanowires (NWs) by ion exchange reaction (IER). This method is based on the exchange of O 2-into S 2-ions at the surface of Cu 2 O in a solution-containing Na 2 S acting as the sulphur ions source. The Cu 2 S overlayers are grown under different experimental conditions by varying the Na 2 S concentration and the duration of the IER process, thus leading to different Cu 2 S nanomorphologies. In particular, when a concentration of 2 mM Na 2 S is used, hexagonal Cu 2 S nanocrystals are formed on the surface of both Cu 2 O CLs and NWs. These nanocrystals are of larger size at the ridges of the Cu 2 O cubes in CLs and at the tips of Cu 2 O in NWs. The high-quality crystal structure and composition of Cu 2 S are confirmed by high resolution transmission electron spectroscopy and X-ray photoluminescence spectroscopy.