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Nitrogen in the bubbling gas was directly fixed into water by pulsed high-voltage discharge. When the discharge occurred, nitrogen could be dissociated to form active N species to take part in the aqueous chemical process. Nitrous acid (HNO2) was primarily produced, which was further converted into nitric acid (HNO3). With the formation of HNO2 and HNO3, the pH of the liquid decreased. The decrease in pH sped up the conversion from HNO2 into HNO3, thus resulted in an increase in the NO2 - concentration at first and a decrease after a turning point. The nitrogen fixation rate with bubbling nitrogen was faster than that with bubbling air in distilled water. By discharge for about 30 min, HNO2 was converted into HNO3 as the final products. Its concentrations were 1.96 mmol . L-1 with bubbling air and 2.34 mmol . L-1 with bubbling pure nitrogen. The energy efficiencies were 2.08 times 10-9 and 2.48 times 10-9 mol . J-1, respectively.