Using sodium thiosulfate (Na2S2O3) and zinc nitrate hexahydrate as initial materials, ZnS nanospheres were prepared under natural lights at room temperature. The ZnS nanospheres as a preformed building block were further assembled into hierarchical nanospheres by microwave (MW) irradiation in a high pure nitrogen-protected atmosphere. X-ray diffraction (XRD), transmission electron microscope (TEM) and X-ray photoelectron spectra (XPS) analytical techniques were used to characterize as-prepared products, revealing that the monodisperse ZnS nanoshperes were assembled with the smaller nanoparticles with a mean diameter of 5 nm. As a result, a novel microwave-induced assembly mechanism was proposed and highlighted. (C) 2007 Elsevier B.V. All rights reserved.