Silver supported on silica, prepared by impregnation method, was investigated using TEM, XRD, UV vis spectroscopy, TPO, H-2 TPR and CO TPR methods, and tested in low-temperature CO oxidation. To reveal the role of metal-support interaction, the Ag catalysts based on silica, pre-treated at 500 (SiO2-500) and 900 degrees C (SiO2-900), were compared. Highly dispersed silver particles (1-4nm) were observed for both Ag/SiO2-500 and Ag/SiO2-900 catalysts. The highest amount of active oxidative species was determined for Ag/SiO2-900 catalysts using TPx methods. The high temperature (900 degrees C) pretreatment of silica support is found favorable for formation of silver species active in O-2 and CO activation and leads to increasing of catalytic activity in CO oxidation. The defect structure of Ag nanoparticles is a possible reason for high activity in low-temperature CO oxidation. (C) 2016 Elsevier B.V. All rights reserved.