Nitric acid (HNO3) and nitrous oxide (N2O) play an important role in the atmospheric chemistry in regulating the global environment and climate changes. In this study, the interaction mechanisms between them have been systematically investigated before and after the electron capture employing the density functional theory in combination with the AIM, NBO, and ab initio molecular dynamics calculations. It was found that HNO3 and N2O can form transient complexes through intermolecular H-bonds. HNNO, OH, and NO2 free radicals can be produced after the electron capture of the formed complexes, providing an alternative source of these radicals in the atmosphere. The present results not only can provide new insights into the transformation of the HNO3 and N2O atmospheric species but also can enable us to better understand the potential role of the free electron in the atmosphere.