A sintered sensor element based on molybdenum oxide (MoO 3 ) has been fabricated. This sensor showed a good sensitivity towards NO and NO 2 gases in the temperature range of 200–500°C. The resistance of the sensor element increased upon the introduction of NO and NO 2 gases. The sensor was also found to be suitable for methane gas; however, it showed a decrease in the resistance upon introduction of the gas. Satisfactory performance of the present sensor to NO 2 , NO and CH 4 at concentrations of 100, 250 and 500ppm, respectively, was obtained.