Several association and switching reactions involving clusters of Na+ ions with stratospheric neutral molecules have been examined at temperatures ?420 K with a flow-tube apparatus. These measurements indicate that sodium componds, NaX, that react with the H3O+⋅nH2O ions in the stratosphere will convert these ions into the clusters NaOH2+⋅nH2O, thereby supporting the recent assignment of these clusters as some of the ions observed during stratospheric rocket and balloon flights. Moreover, the rate constants for the association of Na+ with N2 and CO2, together with the bond dissociation of Na+⋅N2 and Na+⋅CO2 clusters, support the contention that the formation of the sodium cluster ions in the mesoshere can greatly increase the effective rate of electron recombination with sodium ions.