Ionizing irradiation of N2-O2-SO2 mixtures at pressures between 10 and 30 atm produced a white solid product of approximate formula (NO2)2S2O10. When the SO2 was quantitatively consumed in the presence of an excess of N2 and O2, only NO2 and N2O were found in the gas phase as products. The G-value for nitrogen fixation (in the condensed and gas phases) was not large and seldom exceeded unity.