A highly active catalyst (La(0).(7)Ag(0.3)MnO(3)) for simultaneous removal of nitrogen oxides (NOx) and diesel soot is synthesized by solid state method and the catalyst is characterized by XRD, FT-IR, H(2)-TPR, and O(2)-TPD. The results indicate that metallic Ag appears in the La(0).(7)Ag(0.3)MnO(3) catalyst. The concentration of oxygen vacancy and the over-stoichiometry oxygen content also remarkably increase as the substitution increase of Ag(+) for La(3+) at A-site ions. The simultaneous removal of soot particulates and NOx activities are evaluated by a temperature-programmed reaction (TPRe) technique. The superior performance of the La(0).(7)Ag(0.3)MnO(3) catalyst for the reaction is probably due to lots of oxygen vacancy and over-stoichiometry oxygen in the perovskite lattice along with the zero-valence silver. (C) 2010 Elsevier B.V. All rights reserved.