In this Letter, three-dimensional (3D) interconnected networks of ZnO nanowires and nanorods are synthesized by a high temperature solid-vapor deposition process. The nanorods and nanowires have diameters of 20-100 nm and they grow along the c-axis. Due to the diverse orientation of the nanowires grown from a polycrystalline substrate, the networks are formed by a sintering process of the crossed nanowires during growth. The thickness of the multilayer nano-network could be as thick as similar to 30 mu m. The sharp nanowire tips, the high degree of networking, and high surface area of these unique nanonetworks make them a potential candidate for field emission, ultra-sensitive gas sensing, catalysts and filtering. (c) 2005 Elsevier B.V. All rights reserved.