The present invention relates to the field of gas measurements, and more specifically to the field of testing the measuring function of a measuring device (7) for gas measurements, the measuring device (7) including a gas sensor (9) generating at least one output signal. The method includes connecting at least one simulation signal to the measuring device (7) and/or feeding a gas mixture to the measuring device wherein the magnitude of the concentration of a gas to be measured in the gas mixture is known. The invention also relates to a simulation device (1) for connection to the measuring device (7) for gas measurements when testing the measuring function of the measuring device (7). The simulation device (1) generates at least one simulation signal which can attain at least one signal level, wherein a certain signal value corresponds to a certain gas concentration.