Thin films of type-II Bi2O3@Bi2S3 core-shell nanoparticles (NPs) have been assembled on fluorine doped tin oxide (FTO) coated conducting glass substrates via a facile new route. It contains three steps: electrochemical dispersion of a Bi electrode into Bi NPs collected with the FTO substrate, thermal treatment of the assembled thin film of Bi NPs on the FTO substrate into Bi2O3 NPs, and then surface sulfurization of the Bi2O3 NPs. The films of these NPs were characterized by field emission scanning electron microscopy, transmission electron microscope, X-ray diffraction, and Raman spectroscopy. The prepared thin film of Bi2O3@Bi2S3 core-shell NPs displays much better photoelectrochemical performance and photoresponse than both of Bi2O3 NPs without sulfurization and Bi2S3 NPs from complete sulfurization of Bi2O3 NPs, suggesting the advantage of type-II Bi2O3@Bi2S3 core-shell structure. The Bi2O3@Bi2S3 core-shell nanoparticle assembled thin films promise potential applications in photoelectrochemical cells, photodetectors and optoelectronic devices. (C) 2011 Elsevier B.V. All rights reserved.