Quasi-three-dimensional (3D) ZnO nanostructure networks have been grown on silicon substrate by metalorganic chemical vapor deposition (MOCVD). The nanostructures are composed of 1D nanowires and 2D nanowalls. The nanowalls in the nanostructures were g-rowing along [0 0 0 1] and vertically standing on the silicon substrate. Energy dispersive X-ray spectroscopy (EDX) measurement shows that the ZnO nanostructures are 0 rich. Room-temperature photoluminescence (PL) measurement reveals strong ultraviolet (UV) emission and weak green emission, which demonstrates that the nanostructures are with good optical properties. The mechanism of synthesis of the ZnO nanostructure networks is proposed. (c) 2005 Elsevier B.V. All rights reserved.