The uptake of gaseous nitrogen dioxide (NO2) and nitrous acid (HNO2) on aqueous surfaces is determined using a liquid jet technique. Both the loss of the two species from the gas phase and the formation of nitrite and nitrate in the liquid phase are measured. The experimental results are compared with two-dimensional model calculations simulating transport and chemical processes in the gas and liquid phase, The measured uptake of NO2 is much larger than that calculated from the model and literature values for the solubility of NO2 in water indicating, as all other experimental evidence, a reaction of NO2 on the aqueous surface. The measurements also indicate a partial release of HNO2 from the surface to the gas phase. The comparison of experiment and model yields a lower limit of the mass accommodation coefficient of NO2 of alpha greater than or equal to 2 x 10(-4) at 278 K surface temperature, For the mass accommodation coefficient of HNO2 a range from 4 x 10(-3) to 4 x 10(-2) at 278 K surface temperature is obtained.