High-dispersed, well-knit and porous Ag/CO3O4 nanocomposites are prepared via a novel "in situ self-reduction" route, calcining Ag-3[Co(CN)(6)] nanoparticles at different temperatures in air. All samples exhibit an excellent catalytic performance for CO oxidation due to the synergetic effect of nanojunctions between Ag and Co3O4 nanoparticles. The sample prepared at 200 degrees C possesses Ag/Co3O4 nanojunctions at a maximum with the smallest particle size of Ag, displaying the best catalytic activity and excellent stability with a complete CO conversion temperature (T-100) of 100 degrees C. The activity was maintained for more than 18 h and even after the catalyst was exposed to air for two months. Without any pretreatment, Ag/Co3O4 catalysts prepared in this paper show super catalytic performance compared with other oxide supported-Ag catalysts reported in recent years. (c) 2014 Elsevier B.V. All rights reserved.