ZnWO4 nanoparticles were successfully synthesized by microwave-solvothermal method. Subsequently, the incipient wetness procedure was used to load WO3 into ZnWO4 matrix and to form the WO3/ZnWO4 composites with different morphologies. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), Raman spectrophotometry, and electron microscopy (EM) were used to characterize the phase, oxidation state, composites, and morphology. According to the Scherrer formula and the Brunauer-Emmett-Teller (BET) adsorption, average crystallite sizes of the nanopartides are less than 30 nm and 45 nm, respectively, larger than the direct measurement by TEM. The 3.23 eV direct energy gap (E-g) and the 478 nm emission wavelength of 3 mol%WO3/ZnWO4 composites were determined by UV-visible absorption and photoluminescence (PL) spectroscopy. The photocatalytic degradation of methylene blue (C16H18N3SCl) was greatly enhanced by WO3 loading in ZnWO4 matrix to form WO3/ZnWO4 composites. In this research, 3 mol% WO3-loaded ZnWO4 offered the best photodegradation performance of methylene blue at 36.21% within 300 min and 55.54% within 480 min under UV light irradiation. (C) 2015 Elsevier B.V. All rights reserved.