Relative rate constants for the reactions of CO3-(H2O)(n), HCO3-(H2O)(n), NO3-(H2O)(n), and NO3-(HNO3)(n) with H2SO4 have been measured for n = 0-2, 0-2, 0-3, and 0-3, respectively. All rate constants have been found to occur in the ratio expected for the collisional values. This strongly indicates that the reactions proceed at the collision rate, and we assign absolute rate constants on the basis of this assumption. The present results show that all ions previously used for chemical ionization detection of H2SO4 concentrations in the atmosphere react rapidly, as has been previously assumed.