Compared with other gas-phase analytes, the coexistence and competing effect of moisture component has long faced great difficulty and technical challenge for the reliable detection of chemically oxidizing active H2O2 vapor (HPV). Recently, our group designed and prepared a chemiresistive sensor based on conductive films of poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and PEDOT:PSS/PEDOT to achieve direct detection of HPV at ppm level. Specially, the hydrophobic PEDOT layer was polymerized on the surface of the PEDOT:PSS film by electrochemical method to attenuate the adverse effect of moisture within HPV on the stability and detection performance of the sensing film of PEDOT:PSS/PEDOT.