ZnWO4 nanocrystals have been prepared via a hydrothermal route, and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy. The size and morphology of ZnWO4 nanocrystals were found to depend on the reaction temperature and pH. The length of ZnWO4 nanorod increased with the increase in pH of the hydrothermal solution. An unusual nanoparticle-to-nanorod transformation was observed during the formation of ZnWO4 nanoparticles at pH 11.0 and 180 degreesC. Luminescent properties Of ZnWO4 nanocrystals were investigated by photoluminescence (PL) spectroscopy. (C) 2003 Elsevier Science B.V. All rights reserved.