The selectivity study of the CO2 sensor with respect to other gasses such as N2 and LPG at 523 K are shown in (d) the gas response for CO2 is greater than that of the other gasses at the same concentration of 500 ppm. the stability of La2O3 sensor at 500 ppm over 30 day is checked.the stability of this material is good enough to detect CO2 over a long time as shown in