In the present work the energetics of the N^+ + H_2 -> NH^+ + H reaction was investigated by measuring the rate coefficient of the reverse reaction NH^+ + H -> N^+ + H_2. The measured reaction rate coefficient was at least one order of magnitude lower than the Langevin rate coefficient (ALMOST EQUAL TO 10-10 cm^3s^(-1)).
Comparison of the data with theoretical calculations and other measurements that were carried out earlier in our department suggests that the reverse reaction is endothermic.