Nanoscaled MoO3 particles loaded on ZnO nanorods (ZnO NRs) were synthesized via a hydrothermal-precipitation method. X-ray diffraction, field emission-scanning electron microscopy, high resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, UV-vis absorption and photoluminescence studies were used to characterize the structures, morphologies and optical properties of the composites. The results showed that pure orthorhombic phase of alpha-MoO3 nanoparticles with average sizes of 15-21 nm were well dispersed on the surface of ZnO NRs. The MoO3/ZnO NR composites also showed high charge separation efficiency and center dot OH generation ability as evidenced by their photoluminescence spectra. The photocatalytic studies revealed that the MoO3/ZnO NRs showed superior visible-light degradation rate for herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) compared with the pure ZnO NRs. Such enhancement might be attributed to the high separation efficiency of photogenerated electron-hole pairs based on the cooperative roles between bi-components of MoO3 and ZnO NRs. The photocatalytic studies also showed that various parameters such as the MoO3 content in the composite, MoO3/ZnO NRs amount, initial 2,4-D concentration and solution exerted their individual influence on the 2,4-D degradation. Moreover, the MoO3/ZnO NRs could be easily recovered and reused due to their one-dimensional nanostructural property. (C) 2013 Elsevier B.V. All rights reserved.