ZnS/ZnO interfacial heterojunction with high emission quantum yield (about 57%) was synthesized through a simple one-step solvent-thermal method. Our synthesis involves in the fabrication of hexagonal wurtzite-8H ZnS nanocrystals and its heterojunction reaction with ZnO decomposed from zinc acetate dehydrate. The ZnS/ZnO heterostructure quantum dots (QDs) are well fitted to the Gaussian function into three emission bands centered at 415, 450, and 490 nm, respectively. The stability of ZnS/ZnO heterostructure QDs is far superior to that of ZnS QDs, and the emission quantum yield of ZnS/ZnO heterostructure QDs is higher than that of ZnO QDs. The heterostructure is clearly observed in transmission electron microscopy pictures. The effects of the interfacial structure on Zn 3d, O 2p and the Fermi level of the ZnS/ZnO QDs are also discussed in the X-ray photoelectron spectroscopy spectra. (c) 2010 The Electrochemical Society. [DOI: 10.1149/1.3507260] All rights reserved.