The charge exchange of O+(2D) with N2+ is one of the major sources of N2+ in the thermosphere. Its rate coefficient k was measured in the laboratory to be ≂1¿10-9 cm3 s-1. Model calculations using this reaction rate yielded N2+ and NO+ concentrations in excess of those measured by the Atmosphere Explorer (AE) satellites. It was deduced that a smaller value of ~1¿10-10 cm3 s-1 was necessary in order to provide agreement between calculated and measured values of N2+ and NO+. Since the laboratory measurements were performed at high ion energies, it was suggested that the charge exchange of O+(2D) with N2 proceeded faster in the laboratory than in the thermosphere where only thermal energies are acquired by the ions. However, recent laboratory studies by two independent groups have confirmed a value of 8¿3¿10-10 cm3 s-1 for the rate coefficient of the charge exchange of O+(2D) with N2 at thermal energies. In this paper we draw the attention to the fact that the resonant reaction O+(2D)+N2(X1&Sgr; +g)v=0 ⋅N2+(X2&Sgr;+g)v=5+O(3P) has not been considered in previous studies of N2+ chemistry in the ionosphere. We show here that the inclusion of the back reaction as a new sink for N2+ resolves the discrepancy between the laboratory and aeronomically deduced results.