In this work, sphere-like Ag/Bi2O3 nanocomposites with the average size of ca. 170 nm were successfully synthesized by simple deposition-precipitation method. The antibacterial activities of as-prepared Ag/Bi2O3 nanocomposites were evaluated by minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC) and colony counting methods. It was found that Ag/Bi2O3 nanocomposites displayed greatly improved antibacterial ability against common pathogenic Gram-positive and Gram-negative bacteria in comparison with single-component Bi2O3 nanospheres. More importantly, Ag/Bi2O3 nanocomposites exhibited remarkably outstanding antibacterial activities against clinical drug-resistant bacteria. The antibacterial activity of Ag/Bi2O3 nanocomposite increased with the increase of Ag content and 15 wt % Ag/Bi2O3 nanocomposites showed the highest antibacterial activity. Furthermore, a plausible antibacterial mechanism of Ag/Bi2O3 nanocomposite was proposed. It was believed that the enhanced generation of H2O2 could lead to the membrane leakage of cytosol and the inactivation of respiratory chain dehydrogenaes, which was possibly responsible for the enhanced antibacterial activities of nanocomposites. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.