Hollow copper doped ZnS (Cu-ZnS) nanostructures were synthesized by sonochemical approach and characterized well using various analytical tools. TEM images show that the prepared copper doped ZnS crystallites have a hollow-sphere-like self-assembled nanostructure. In Fourier transform infrared (FT-IR) spectra, a noticed splitting of the ZnS peak at 1110 cm(-1) into two peaks at 1124 and 998 cm(-1) for copper doped ZnS indicates that the copper atom can be partially substituted in the zinc as Cu-S-Zn. Such a bonding interaction between copper and zinc ions toward sulfur was also established from XRD and XPS analysis. Tuning of the band gap from 3.65 to 2.89 eV was successfully achieved upon doping copper (0-5%) into ZnS. The catalytic activity of hollow Cu-ZnS nanosructures was tested by photosplitting of water containing Na2S via visible light irradiation.