In the study, a novel gas sensor is presented for detection of aromatic hydrocarbons (benzene, toluene and xylene), consisting of a quartz substrate, Pt electrodes and a WO 3 thin film. Oxidation occurs on the heated WO 3 sensing layer as an aromatic hydrocarbon is present in the atmosphere, which causes a resistance variation of the WO 3 thin film. From the measured resistance change, the aromatic hydrocarbon concentration is then computed. It is found that the crystalline structure is more perfect as the as-sputtering substrate temperature is 300°C, the WO 3 thin film is annealed and the sputtering time is more than 6 hrs. At the optimal working temperature of 300°C, the experimental results show that the sensor has a rapid response time and a high degree of sensitivity for detection of benzene, toluene and xylene.