CuO nanostructures were synthesized by thermal evaporation method. Using Cu metal plate at temperature of 400oC for 24 hrs in one atmosphere of oxygen and studied structural and gas sensing properties. The CuO nanostructured were investigated by the stereo microscope (image analyzer), X-ray diffraction, scanning electron microscope. The diameter of CuO nanowires vary from 10 nm to 50 nm and length of several 10 micrometers. The sensitivity of CuO nanostructures and response were performed at room temperature for ethanol and CO2 sensor.