A series of manganese oxide catalysts supported on oxidized multi-walled carbon nanotubes for low temperature selective catalytic reduction of nitrogen oxides (NOx) with NH3 in the presence of excess O-2 was prepared by a simple impregnation method. These catalysts were characterized by N-2 adsorption, TEM, XRD and H-2-TPR methods. The effects of reaction temperature, MnOx loading, and calcination temperature were investigated. Under the reaction conditions of 483 K, 1 bar, NO = NH3 = 900 ppm, 5 vol% O-2, GHSV = 30,000 h(-1), and 12 wt% MnOx, NOx conversion and N-2 selectivity of 91 and 99 %, respectively, were obtained. The LTSCR activity was suppressed in the presence of 100 ppm SO2 and 2.5 vol% H2O at reaction temperatures below 573 K, but it was reversible to its initial level after heating and sweeping the catalyst at 573 K for 2 h in Helium.