In this work, a H2S sensor formed from hybrid of WO3 and polypyrrole (PPy) by mechanical mixing was produced. The gas-sensing properties of the hybrid materials were studied and compared with those of PPy and WO3. It was found that PPY/WO3 materials can complement the drawbacks of pure PPy and WO3 to Some extent. PPY/WO3 materials with varies PPy mass percent (1%, 3%, 5%, 10%, 20%) had better reversibility than PPy, and also had higher sensitivity than WO3 when operated at 90 degrees C. The sensing mechanism of PPy/WO3 materials to H2S was presumed to be the synergism of PPy and WO3 or the effect of p-n heterojunctions. (c) 2006 Elsevier Ltd. All rights reserved.