This study reports the production of Gd(III)-doped ZnO nanorods on the glass substrate via spin coating and hydrothermal routes, respectively, and investigation of CO2 gas sensing properties. It was determined that the response of the ZnO nanorods to CO2 gas under the open-air atmosphere increases with doping concentration (up to 3 mol %) and temperature. The optimum operating temperature of the sensors was determined as 200 degrees C, and the response of the 3 mol % doped sample was about 85% at this temperature. The response and recovery times to 100 ppm concentration of CO2 gas were determined as 30 and 25 s, respectively. The 3 mol % Gd(III)-doped ZnO nanorods sensor has quite high sensitivities for CO2 gas compared to acetone and ethanol. In addition, it was observed that the 3 mol % Gd(III)-doped ZnO nanorod sensor maintained its response stability against CO2, acetone, and ethanol gases for 30 days.