The current gas sensors have a problem in selectivity of gas and using the dynamic response is one solution to identify the gas type. In the dynamic response, the information from the non-linear phenomena under the transient temperature conditions was used to recognize various gas types with a single sensor element. The mechanism was slightly revealed so far and this work aimed at determining the key factors of the dynamic response. Non-doped SnO2 films were prepared by a liquid phase deposition (LPD) method to control the morphology of the film and the components of the sensor. Nano-scale control in the thickness was demonstrated by the simple LPD process. The gas type was successfully identified even with the non-doped SnO2 films. The film thickness did not largely affect the profile of the signal and the dynamic response was considered to be due to basic phenomena between the gas and the sensor material itself such as adsorption and desorption.