ZnGa2O4 crystals in the shapes of polyhedron-like, rod-like, and irregular particle have been successfully synthesized using different gallium sources. namely, GaO(OH), Ga-2(SO4)(3)center dot 16H(2)O, and Ga2O3, by a hydrothermal method and characterized by X-ray diffraction, transition electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometer (EDX), ultraviolet-visible (UV-vis) absorption spectroscopy, and fluorescence spectrophotometer. From the experimental results, it was revealed that the gallium source played an important role in the formation of the products with different morphologies and sizes. The absorption and corresponding emission peaks of ZnGa2O4 obtained from Ga2O3 and Ga-2(SO4)(3)center dot 16H(2)O shifted to a higher energy when compare to these peaks of ZnGa2O4 obtained from GaO(CH), respectively. These phenomena were attributed to the quantum-size effect in the nanosized ZnGa2O4. (c) 2005 Elsevier B.V. All rights reserved.