The copper oxide (CuO) nanoneedles were synthesized by a simple hydrothermal method. Field emission scanning electron microscopy revealed the formation of high-density CuO nanoneedles with ultrathin nanotip at low temperature. The X-ray diffraction (XRD) results showed that the CuO nanoneedles have monoclinic structure with single crystalline phase. High-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction results also assisted the products single crystalline nature. The magnetic properties of CuO nanoneedles were studied using a superconductor quantum interference device ( SQUID) magnetometer, and revealing a ferromagnetic behavior of the CuO nanoneedles. The coercivity of CuO nanoneedles at 3 K was estimated to be 42 Oe. These CuO nanoneedles may be implicated to various applications such as drug delivery, magnetic resonance imaging and field emission devices. (C) 2008 Elsevier B. V. All rights reserved.