The reactive uptake coefficients, gamma, of NO3 onto aqueous solutions containing ions X(-) = HSO3-, SO32-, HCOO-, CH3COO-, and OH- were measured at 273 +/- 1 K using a wetted-wall flow tube reactor. The values of (HD)-D-2/k (H = Henry’s law coefficient, D-/ = diffusion coefficient in the liquid phase, and k = second-order rate coefficient for the liquid phase reactions of NO3 with X(-)) for the reactive uptake of NO3 were determined by measuring gamma as a function of liquid phase reactant concentration. The linear correlation between the measured rate coefficients and those for corresponding SO4- reactions, and the dependence of the measured rate coefficients on the redox potential of the X/X(-) pair suggest that the NO3 + X(-) reactions proceed by electron transfer. The atmospheric implications of these findings are briefly discussed.