Nitrogen　oxide　(NOx)　is　one　of　the　key　factors　contributing　to　air　pollution,　and　selective　catalytic　reduction　with　ammonia　(NH3-SCR)　is　widely　used　for　denitrification　(de-NOx).　To　effectively　deal　with　the　NOx　pollution,　it　is　urgent　to　develop　efficient　catalyst　working　at　below　300　°C　with　a　wide　operating　temperature　window.　Herein,　a　series　of　ferromanganese　oxides　(MnFeOx)　nanobelts　are　bimetallically　modified　with　niobium　(Nb)　and　neodymium　(Nd)　for　the　first　time　via　electrospinning　method.　The　resultant　MnFeNbNdOx　catalysts　present　improved　low-temperature　de-NOx　performance　and　sulfur　dioxide　(SO2)　tolerance,　particularly　MnFeNb0.2Nd0.1Ox　who　achieves　a　NOx　conversion　up　to　over　90　%　during　the　range　of　120–330　°C　and　an　enhanced　tolerance　of　water　(H2O)　and　SO2.　Experimental　and　theoretical　calculations　confirm　that　strong　adsorption　of　nitric　oxide　(NO)　and　ammonia　(NH3)　and　weak　adsorption　of　SO2　with　the　synergy　of　Nd,　Nb　and　Mn　enable　MnFeNb0.2Nd0.1Ox　excellent　SCR　activity　and　good　SO2　tolerance.　In-situ　diffuse　reflectance　infrared　Fourier　transform　spectra　(DRIFTS)　further　reveal　that　the　de-NOx　reaction　over　MnFeNb0.2Nd0.1Ox　follows　both　Eley-Rideal　(E-R)　and　Langmuir-Hinshel-wood　(L-H)　mechanisms.　This　study　will　inspire　the　further　design　and　study　of　the　synergy　of　transition　metals　and　rare　earth　elements　for　de-NOx.　©　2022　Elsevier　Ltd