Hydrogen peroxide (H₂O₂) is widely used aqueous solution for oxidation, disinfection and sterilization, and its detection is very important in the fields of biological health and environment. The main detection methods of H₂O₂ include colorimetric, electrochemical, enzymatic and fluorescence analysis. However, due to the influence of moisture and oxidation, it is very scarce to realize the simple, convenient, real-time and efficient detection technology for hydrogen peroxide vapor (HPV). Recently, our group proposed to add ammonium titanyl oxalate (ATO) to the sensing film composite system to prepare a chemosensor based on PEDOT:PSS-ATO/PEDOT composite film, and explored the influence of various material systems on its HPV sensing performance both giving electrical and colorimetric response. This study was expected to realize a practical HPV sensor as well as promote the further application of PEDOT-based composites in the field of chemosensors.