The catalytic performance and promotional mechanism of tungstation for selective catalytic reduction of NO by methane over In-loaded tungstated zirconia (In/WZr) were investigated. A clear improvement of catalytic activity was found over In/WZr catalysts. The highest NO conversion of 70% was achieved over a 1% In/WZr catalyst at 450°C and 12,000h −1 . In contrast, the maximum NO conversions of WZr, ZrO 2 and In/ZrO 2 were only 12%, 31% and 20%, achieved at 500, 650 and 600°C, respectively. Tungstation was observed to influence the properties of catalysts in three aspects: (i) modify the existent state of surface indium species; (ii) determine the activation species of CH 4 ; (iii) cooperate with the loading of indium to enhance the formation and reduction of the intermediates. Differences in the existent state of indium and the activation species of CH 4 result in different catalytic activities and mechanisms for CH 4 -SCR of NO. X-ray photoelectron spectroscopy measurements and Py-IR analysis showed that indium species on the In/ZrO 2 catalyst was in the In 2 O 3 bulk phase due to the lack of Brønsted acid sites. However, the tungstated In/WZr catalyst possessed strong Brønsted acid sites, which was beneficial to the formation of active InO + species. DRIFTS studies further revealed the reaction intermediates of CH 4 -SCR of NO on the tungstated and the untungstated catalysts. On In/ZrO 2 and ZrO 2 , the activation species of CH 4 was the fully oxidized products CO 2 and H 2 O. While on WZr and In/WZr, HCOO − , the real reductant for CH 4 -SCR of NO, was detected as the main intermediate species. In addition, the formation of HCOO − and the reduction of nitrate species were greatly accelerated by the synergistic effect between InO + and tungstation, which might explain the higher catalytic activity of In/WZr in comparison with WZr and In/ZrO 2 .