In real-life conditions of use, gas identification by a tin oxide gas sensor is quite difficult because of its lack of selectivity and humidity and temperature dependency. To solve these problems, these kind of sensors are grouped in an array, and powerful pattern recognition methods are used. In this work, a preliminary study is presented to show the influence of relative humidity on the response to a dry refrigerant gas concentration. Afterwards, we present the characterisation of three TGS type gas sensors (TGS 800, TGS 813 and TGS 832) submitted to multiple relative humidity rates in synthetic air. Their responses are presented in terms of dynamic and steady-state responses. Simulated models are proposed to approach the sensors' responses and could be used in pattern recognition methods.