This paper reports CuO straw-like nanostructures (nanostraws) synthesized on copper foil substrate through a simple solution method at room-temperature without using any template. The microstructure and morphological of CuO nanostraws were investigated by the X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM), revealing that the straw-like nanostructures were exhibited the nanocrystalline nature with monoclinic structure and monodispersed in large quantity. The possible growth mechanism for the formation of CuO nanostraws products was discussed in detail. In addition magnetic properties and field emission properties of as-obtained products were also investigated. (C) 2008 Elsevier B. V. All rights reserved.