ZnO nanowires can be synthesized in aqueous solution by a dissolution-growth mechanism. These nanowires are single crystalline c-oriented wurtzite. The ZnO rod crystals are eroded to provide the growth precursor of ZnO nanowire. The nanowire is formed on top of the rod crystals when the erosion reaction achieves the equilibrium. The growth pattern of nanowires can be characterised based on the TEM and HRTEM results. The length of the nanowire is rather large because the successive erosion of the rod crystals maintains the low concentration of Zn2 O(OH)2n-2. These nanowires have great application potential in the photoelectric field, such as luminescence, window and electrode material for solar cells, phosphors, piezoelectric transducers and actuators, surface acoustic coatings, varistors, sensors, and so on. This strategy can provide a novel and simple route to obtain ZnO nanowires, even ultralong ZnO nanowires which may improve the properties of nanowire-based devices.