The absorption of NO,(TV) into nitric acid solutions containing a low concentration of hydrogen peroxide was studied in a small packed column. A simple mathematical model developed for this absorption was used for the determination of kinetic parameters relative to NO2 and N2O4 in such solutions. Results obtained at 10, 20 and 30 degrees C lead to the same interpretation: hydrolysis is the main controlling step for tetravalent nitrogen oxides absorption and there is no sensible effect of the acidity on the absorption efficiency. Hydrogen peroxide, however, plays an essential role in solution by preventing the HNO2 decomposition. Our mechanistic and kinetic findings were validated as the model has worked with fair success in predicting NO, removal efficiencies in a pilot-scale packed column.