The detection of ozone is very important and at low doses. Ozone is a secondary pollutant (primary pollutants are NOx, which with heat generate ozone) that can seriously damage the ENT sphere in humans. Brief exposure to ozone can cause eye, nasal and throat irritation, coughing, and headaches. Exposure to high concentration can cause decreased lung function. Ozone is strongly linked to asthma and can make symptoms worse. In France, the information threshold is around 90 ppb and the alert threshold is 180 ppb. In the US it's even lower (75 and 150 ppb). In order to integrate new sensitive materials for ozone detection, In2S3 films were prepared via a facile pyrolysis spray method. Physical properties of the obtained samples were investigated by GIXD, AFM, SEM, EDS, XPS, PL and UV–visible spectroscopy techniques. The sensor shows high sensitivity to ozone and the limit of detection is as low as 40 ppb. The optimal working temperature is found to be 160 °C and the detection mechanism is based on dissociative chemisorption. In addition, the gas sensor exhibits acceptable rapidity and good selectivity at 160 °C. This study demonstrates the possibility of producing inexpensive and sensitive ozone gas sensors based on sprayed In2S3 films.