Pt-MnOx catalysts without any alkali or transition metals were prepared and their performance in the selective catalytic reduction (SCR) of NO by H-2 was examined. Their physicochemical properties were investigated using X-ray diffraction (XRD), extended X-ray adsorption fine structure (EXAFS), and X-ray photoelectron spectroscopy (XPS). The adsorption and removal of NO during H-2-SCR were monitored by an in situ FT-IR spectrophotometer. The co-presence of MnO and MnO2 on Pt-MnOx was confirmed by EXAFS and XPS. NO was adsorbed on them as nitrate and nitrite, which were subsequently transformed to NHx species by the introduction of H-2. The NHx species adsorbed on the acid sites of manganese oxide were active in the reduction of NO, although a direct reduction by H-2 was also possible. The conversion of NO over the Pt(2.0)-MnOx catalyst was maximized to 64% at around 100 degrees C and fell with further increases in temperature. The N-2 yield over the Pt(2.0)-MnOx catalyst was 30% at the same condition, indicating that about a half of NO was converted to N-2. On the contrary, the Pt(2.0)/SiO2 catalyst exhibited very low N-2 yield, 10%, because N2O was highly produced. The reaction between the hydrogen atoms activated on the platinum and the activated NO on the manganese oxide was considered essential for H-2-SCR, and NH3 that formed as an intermediate effectively participated to the selective reduction. (c) 2011 Elsevier B.V. All rights reserved.