Flower-like SnO 2 nanopowders prepared by a hydrothermal method were surface modified with palladium via impregnation. The crystal structure, morphology, and surface chemistry states of the samples were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), respectively. The gas sensing performances were also investigated. For a hydrothermal temperature of 220°C, flower-like SnO 2 nanoparticles consist of nanorods with diameters of 40nm and lengths of 100nm. The XPS and XRD results reveal that palladium exists in the Pd 0 chemical state but the crystal is too small to be detected. The 0.3wt% Pd modified SnO 2 sensor shows better sensitivity, up to 21, for 70μL/L ethanol gas at an optimal working temperature of 250°C. The quick response time (3s) and fast recovery time (∼20s) are the main characteristics of this sensor.