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Molecular hydrogen (H₂) is now considered among the most prominent substitute for fossil fuels. The environmental impacts of a hydrogen economy have received more attention in the last years, but still, the knowledge is relatively poor. In this work, the reaction of H₂ with NO₃ radical (the dominant night-time detergent of the atmosphere) is studied for the first time using high-level composite G3B3 and modification of high accuracy extrapolated ab initio thermochemistry (mHEAT) methods in combination with statistical kinetics analysis using non-separable semi-classical transition state theory (SCTST). The reaction mechanism is characterized, and it is found to proceed as a direct H-abstraction process to yield HNO₃ plus H atom. The reaction enthalpy is calculated to be 12.8 kJ mol⁻¹, in excellent agreement with a benchmark active thermochemical tables (ATcT) value of 12.2 ± 0.3 kJ mol⁻¹. The energy barrier of the title reaction was calculated to be 74.6 and 76.7 kJ mol⁻¹ with G3B3 and mHEAT methods, respectively. The kinetics calculations with the non-separable SCTST theory give a modified-Arrhenius expression of k(T) = 10⁻¹⁵ × T^0.7 × exp(−6120/T) (cm³ s⁻¹) for T = 200–400 K and provide an upper limit value of 10⁻²² cm³ s⁻¹ at 298 K for the reaction rate coefficient. Therefore, as compared to the main consumption pathway of H₂ by OH radicals, the title reaction plays an unimportant role in H₂ loss in the Earth’s atmosphere and is a negligible source of HNO₃.