An electronic nose based on a TGS type sensor array for the main detection of Forane R134a has been characterised under closely controlled gas temperature and humidity conditions. This paper presents the dependence of the TGS sensor array to the gas temperature and the relative humidity rate values. A model is proposed for the sensor array behaviour for each of these parameters. Afterwards, the importance of these two atmospheric parameters is underlined and the need to control or to include them into a database is proven. We present the ability to identify the target gas with the discriminant factorial analysis method even if the relative humidity or the gas temperature differs from the nose database learning process.