Abstract: The hydrogen sensitivity of a hydrogen sensor with the Nafion112 membrane as electrolyte was studied under different working environments.The results show that the hydrogen sensor has good hydrogen sensitivity and can quickly detect a tiny hydrogen leak.The generated electromotive force increases linearly with the logarithm of hydrogen volume fraction in the range of (500 to 3000)×10^-6,which provides a basis for calibrating the relationship between hydrogen content and the sensor's electromotive force.The electromotive force decreases with the increase in temperature under a fixed humidity condition.The effect of humidity on the sensor's electromotive force also relates to temperature.When the temperature is low,the electromotive force decreases with the increase in humidity;while the temperature is high,the electromotive force increases with the increase in humidity.