Pressurized oxy-combustion is a promising technology that can significantly re-duce the energy penalty associated with first generation oxy-combustion for CO<
sub>
2<
/sub>
capture in coal-fired power plants. However, higher pressure enhances the production of strong acid gases, including NO<
sub>
2<
/sub>
and SO<
sub>
3<
/sub>
, aggravating the corrosion threat during flue gas re-circulation. In the flame region, high temperature NO<
sub>
x<
/sub>
exists mainly as NO, while conversion from NO to NO<
sub>
2<
/sub>
happened in post-flame region. In this study, the conversion of NO ? NO<
sub>
2<
/sub>
has been kinetically evaluated under representative post-flame conditions of pressurized oxy-combustion after validating the mechanism (80 species and 464 reactions), which includes nitrogen and sulfur chemistry based on GRI-MECH 3.0. The effects of residence time, temperature, pressure, major species (O<
sub>
2<
/sub>
/H<
sub>
2<
/sub>
O), and minor or trace species (CO/SO<
sub>
x<
/sub>
) on NO<
sub>
2<
/sub>
formation are studied. The calculation results show that when pressure is increased from 1 to 15 bar, NO<
sub>
2<
/sub>
is increased from 1 to 60 ppm, and the acid dew point increases by over 80�C. Higher pressure and temperature greatly reduce the time required to reach equilibrium. With increasing pressure and decreasing temperature, O plays a much more important role than HO<
sub>
2<
/sub>
in the oxidation of NO. A higher water vapor content accelerates NO<
sub>
2<
/sub>
formation in all cases by providing more O and HO<
sub>
2<
/sub>
radicals. The addition of CO or SO<
sub>
2<
/sub>
also promotes the formation of NO<
sub>
2<
/sub>
. The NO<
sub>
2<
/sub>
formation in a pressurized oxy-combustion furnace can be over 10 times that of an atmospheric air-combustion furnace.