Nd was used as the modifier to improve the NH3-selective catalytic reduction (SCR) performance of MnOx catalyst used in NOx abatement. The results of the activity test indicated that MnNdOx-0.1 catalyst displayed remarkable catalytic activity and N-2 selectivity in the temperature range of 50-300 degrees C. Characterization results proved the enhanced reducibility and the facilitated NH3 and NOx adsorption over MnNdOx-0.1 catalyst, accompanied by the existence of more Mn4+ and surface adsorbed oxygen species over its surface. The results of the in situ diffuse reflectance infrared Fourier transform study pointed out that the NH3-SCR reaction over MnNdOx-0.1 catalyst was mainly under the control of the Langmuir-Hinshelwood mechanism (<= 100 degrees C); when the reaction temperature was over 200 degrees C, the Eley-Rideal mechanism was dominant. More adsorbed NOx and NH3 species over the MnNdOx-0.1 catalyst, along with the activation effect of Nd on the adsorbed reactants, had a facilitation impact on the SCR reaction process over the MnNdOx-0.1 catalyst.