This paper presents the development of gold-doped tin oxide (SnO2) film, realized by radiofrequency (RF) sputtering, which is highly sensitive for carbon monoxide (CO) gas. According to the Occupational Safety and Health Administration (OSHA), human exposure to 50 ppm CO is safe up to 8 h (as permissible exposure limit), but inhalation of higher concentrations of CO can cause headache, dizziness, nausea, etc. Hence, it is imperative to detect CO gas in low concentrations. The receptor films were prepared via reactive co-sputtering of high-purity Sn and Au targets and characterized by x-ray diffraction (XRD), which confirmed the presence of SnO2 and gold. The thin films of pristine SnO2 and gold-doped SnO2 were also examined through field emission scanning electron microscopy (FESEM) images, showing the distinction in their structures. A reasonably enhanced response of ~ 56.4% was exhibited by gold-doped SnO2 compared to 15.5% for pristine SnO2 for 50 ppm CO at operating temperature of each film. © 2020, The Minerals, Metals & Materials Society.