A new simple route for preparing nanocrystals of cadmium and zinc sulfides and their respective core/shell nanostructures in aqueous solution has been developed by precipitation from metal chloride solutions with sodium sulfide in the presence of polyethyleneimine (PEI) hyperbranched polymer. The as-prepared PEI-stabilized nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-visible spectroscopy, and flurospectroscopy. TEM showed homogeneous nanoparticle size. The sizes of cadmium sulfide (CdS) and zinc sulfide (ZnS) nanoparticles were about 7-53 and 4-17 nm, respectively, on using different proportions of PEI. The sizes of the core/shell and multilayered nanoparticles of both compounds were 19-24, 23-35,108-185, and 100-130 nm for CdS/ZnS, ZnS/CdS, CdS/ZnS/CdS, and ZnS/CdS/ZnS compositions, respectively. (C) 2008 Elsevier B.V. All rights reserved.