The influence of lanthanum stoichiometry in Ag-doped (La1-xAgxMn0.9Co0.1O3) and A-site deficient (La1-xMn0.9Co0.1O3-delta) perovskites with x equal to 10, 20 and 30 at.% has been investigated in catalysts for soot combustion. The catalysts were prepared by the amorphous citrate method and characterized by XRD, nitrogen adsorption, XPS, O-2-TPD and TPR. The formation of a rhombohedral excess-oxygen perovskite for Ag-doped and a cubic perovskite structure for an A-site deficient series is confirmed. The efficient catalytic performance of the larger Ag-doped perovskite structure is attributed to the rhombohedral crystalline structure, Ag2O segregated phases and the redox pair Mn4+/Mn3+. A poor catalytic activity for soot combustion was observed with A-site deficient perovskites, despite the increase in the redox pair Mn4+/Mn3+, which is attributed to the cubic crystalline structure. (C) 2016 Elsevier Ltd. All rights reserved.