A study on the low-temperature CO gas sensors based on Au/SnO2 thick film was reported. Au/SnO2 powders were prepared by a deposition-precipitation method. Thick films were fabricated from Au/SnO2 powders. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) analyses were carried out for investigation of morphology and crystalline structure. Au/SnO2 thick film sensors exhibited high sensitivity to CO gas at relatively low operating temperature (83-210 degrees C). We also reported the effect of the calcination temperature of Au/SnO2 on the CO gas sensing behavior. The optimal calcination temperature of Au/SnO2 was 300 degrees C. (c) 2006 Elsevier B.V. All rights reserved.