Abstract: It is difficult for the traditional metal oxide gas -sensing materials to meet the high performance gas -sensing devices requirement due to the low sensitivity, poor selectivity and high working temperature. Nano-sized material with a high specific surface area can improve gas-sensing properties notably. Herein, sin - gle crystalline CuO nanowires with an average 20~30 nm in diameters, 1~5 μm in length are obtained by thermal oxidation copper powders at 330 and 430 °C in air condition. The optimum working temperature of the sensors based on as-prepared CuO nanowires is about 260 °C in 100 ppm ethanol, with the sensitivity of 1.36 and 1.64 respectively. Both the response and recovery time are less than 5 s.