CeO2, Ce(1-x)MXO2, {M = Ru, In} compounds with sensing properties were fabricated using the sol–gel route. The main purpose was to compare the efficiency of CeO2 vs. Ce(1-x)MXO2 doped compounds as gas sensors for NO2 detection. Characterization was performed by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and surface area determination (BET). Measurements of electrical resistance under different conditions of time, concentration and temperature in the presence of NO2 were carried out. Ruthenium inclusion increased the CeO2 sensor response in a great extent, gas response (S) = 1.8 for CeO2 vs. gas response (S) = 350 for Ce0.95Ru0.05O2 and gas response (S) = 35 for Ce0.95In0.05O2. This behavior is reported by the first time. Our results demonstrate that ruthenium or indium inclusion has been beneficial for CeO2. Conclusively the materials herein described could be applied as NO2 gas sensors.