The sensitive composite material was prepared by loading Pt and La2O3 into ultrafine In2O3 matric material (8 nm) synthesized by microemulsion method. A highly selective ethanol gas sensor was developed based on hot-wire type gas sensor, which was sintered in a bead (0.8 mm in diameter) to cover a platinum wire coil (0.4 mm in diameter). The gas sensor was operated by a bridge electric circuit. The influences of La2O3 and Pt additives on C2H5OH sensing properties of In2O3-based gas sensor were discussed. The addition of La2O3 resulted in a prominent selectivity for C2H5OH, and the addition of Pt improved the response rate to C2H5OH without affecting the sensitivity. The temperature and humidity characteristics of the sensor output were also investigated. The selective sensor had low power consumption, significantly minor humidity and temperature dependence, high selectivity and prominent long-term stability. (c) 2006 Elsevier Ltd. All rights reserved.