WO3-Cr2O3 semiconducting thin films were prepared by sol-gel method. Acetone gas sensing properties were investigated. Monoclinic phase was obtained as determined by X-ray diffraction after WO3-Cr2O3 films were sintered in oxygen atmosphere for 1 h at 500 degrees C (quenched after sintering). Porous structure was observed by using field emission scanning electron microscopy. Electrical properties were studied by conductivity measurement. The acetone vapor sensing properties of these thin films were found strongly influenced by the porous structure, the content of Cr2O3, the sintering temperature, and the cooling way. As-prepared WO3-Cr2O3 thin films exhibit excellent acetone vapor sensing properties with the maximum sensitivity similar to 8.91 at 320 degrees C in air atmosphere with fast response and recovery time. (C) 2011 Elsevier B.V. All rights reserved.