Abstract: A sensor for detecting the presence of gas and methods for use. The sensor has a low sensitivity to relative humidity and high sensitivity to the presence of gases such as carbon monoxide. The sensor is comprised of ternary oxides of the formula Cr2−x(M1zM21−z)xO3 with M1=Fe or Mn, M2=Fe, Mn, or Al, 0.005≦x≦1.95, 0.005≦z≦0.995; ternary oxides of the formula Cr2−x(M1zM21−z)xO3 with M1=Fe or Mn, M2=Ti, 0.005≦x≦1.95, 0.005≦z≦0.45; or quaternary and quinternary oxides of the formula Cr2−x((M1aM2bM3c)zM41−z)xO3 with M1=Fe, M2=Mn, M3=Al, and M4=Ti, 0≦a,b,c≦1, 0.005≦x≦1.95, and 0.005≦z≦0.45.