Ag-M (M: Fe, Co, Ni, Cu) bimetal catalysts supported on SiO2 were prepared by galvanic deposition (GD) method. HAADF-STEM observation and EDX elemental mapping showed that Ag was successfully introduced on Fe, Co, Ni, and Cu particles using the GD method. Ag-Fe, Ag-Co, and Ag-Cu catalysts showed Janus structure that is Ag nanoparticles (NPs) on the 3d metals. On the other hand, Ag-Ni catalyst showed core-shell like structure composed of small Ag NPs (<10 nm) or thin layer on Ni particles. The catalytic activities of Ag-M bimetal catalysts were evaluated by CO oxidation reaction. All Ag-M bimetal catalysts showed higher catalytic activities than Fe, Co, Ni, Cu, and Ag mono-metal catalysts. In particular, Ag-Ni bimetal catalyst having core-shell like structure showed remarkable enhancement of the catalytic activity. (C) 2016 Elsevier B.V. All rights reserved.