A semiconductor ethanol sensor was developed using ZnO-CuO and its performance was evaluated at room temperature. Hetero-junction sensor was made of ZnO-CuO nanoparticles for sensing alcohol at room temperature. Nanoparticles were prepared by hydrothermal method and optimized with different weight ratios. Sensor characteristics were linear for the concentration range of 150-250 ppm. Composite materials of ZnO-CuO were characterized using X-ray diffraction (XRD), temperature-programmed reduction (TPR) and high-resolution transmission electron microscopy (HR-TEM). ZnO-CuO (1:1) material showed maximum sensor response (S = R-air/R-alcohol) of 3.32 +/- 0.1 toward 200 ppm of alcohol vapor at room temperature. The response and recovery times were measured to be 62 and 83 s, respectively. The linearity R-2 of the sensor response was 0.9026. The sensing materials ZnO-CuO (1:1) provide a simple, rapid and highly sensitive alcohol gas sensor operating at room temperature. (C) 2012 Elsevier Ltd. All rights reserved.