Perovskite-type compounds (La1-xAgx)Mn0.9Co0.1O3 (x = 0.0, 0.1, 0.2, 0.3), prepared by the amorphous citrate method, have been investigated as catalysts for soot combustion. The catalysts were characterized by nitrogen adsorption, XRD, SEM, TPR, O-2-TPD, and XPS techniques. The silver addition to the perovskites produces a slight modification of the specific surface area and crystalline structure, while a new source of surface oxygen that comes from the interaction between O- and the low-coordinated metal site was detected. The results suggest that, during soot combustion, the activity of these materials is improved by an increase of the surface silver and superoxide ion content, responsible of the higher capacity for oxygen transfer from the catalyst to the carbons in the solids with higher Ag content.