Hydrogen sensors able to perform measurements in real time in anaerobic environment such as natural gas (NG) will greatly help the development of power to gas technology. For now, thermal conductivity (TC) gas sensors and Pd thin film based sensors have demonstrated their capability to measure H2 in air and N2 but there is still lack of testing in natural gas environment. In this study, the sensing performances (response, hysteresis, response time and selectivity) of two sensors were assessed in three anaerobic environments: N2, CH4, and NG. The first one is a homemade resistive sensor based on a PdAu thin film and the second one is a commercial thermal conductivity sensor. While most performances are equivalent for both technologies, only the PdAu sensor is able to detect selectively H2, without any interfering effect with NG components. Thus, Pd based thin film sensors are promising for H2 detection in anaerobic environments.