Novel copper sulfide (CuS) hollow spheres composed of nanoflakes were synthesized under hydrothermal conditions by treating copper (II)–thiourea complex from CuSO4·5H2O and thiourea at 180°C for 24 h. When increasing the reaction temperature, much smaller hexagonal CuS nanoflakes generated from copper (II)–thiourea complex formed and self-assembled into hollow spheres. The products were characterized by means of X-ray powder diffraction scanning electron microscopy and field emission scanning electron microscopy. It is found that the reaction temperature and copper (II)–thiourea complex are of importance to form hollow spherical superstructures. A possible mechanism is also discussed.