A　series　of　Ce-x-Mn-Ti-y　catalysts　were　synthesized　using　the　coprecipitation　method,　and　sodium　carbonate　solution　was　used　as　a　precipitant.　The　various　catalysts　were　assessed　by　selective　catalytic　reduction　of　NOx　with　NH3,　and　characterized　by　X-ray　diffraction,　Raman　spectroscopy,　H-2　temperature-programmed　reduction,　NH3　temperature-programmed　desorption,　and　X-ray　photoelectron　spectroscopy　to　investigate　the　physicochemical　properties,　surface　acidity,　and　redox　abilities　of　the　Ce-x-Mn-Ti-y　catalysts.　The　Ce-0.1-Mn-Ti-0.1　catalyst　exhibited　the　best　catalytic　performance　(more　than　90%　NOx　conversion　in　the　range　of　75　to　225　degrees　C),　as　a　result　of　proper　redox　ability,　abundant　acid　sites,　high　content　of　Mn4+　and　Ce3+,　and　surface-adsorbed　oxygen　(O-S).　The　results　of　in　situ　DRIFT　spectroscopy　showed　that　the　NH3-SCR　reaction　followed　both　the　E-R　and　L-H　paths　over　the　Ce-0.1-Mn-Ti-0.1　catalyst,　and　it　occurred　faster　and　more　sharply　when　it　mainly　abided　by　the　E-R　mechanism.