The rate constants for reactions of hydroxyl(OH), sulfate (SO/sub 4//sup -/), phosphate (HPO/sub 4//sup -/), and chloride radicals (Cl/sub 2//sup -/) with the first four homologues of tetraalkylammonium cations were determined by the spectrophotometric pulse radiolysis method. The reactivity of tetraalkylammonium cations toward these radicals increases with increasing number of C-H bonds in the molecule. Intercomparison of the rate constants for the different radicals shows a trend characteristic for a mechanism involving hydrogen abstraction, e.g., k/sub OH+R/sub 4/N/sup +/ > k/sub SO/sub 4//sup -/+R/sub 4/N/sup +/ > k/sub HPO/sub 4//sup -/+R/sub 4/N/sup +// > k/sub Cl/sub 2//sup -/+R/sub 4/N/sup +/. The ratios of the reactivities are in good agreement with those reported for other aliphatic compounds which undergo hydrogen abstraction. The reactivities of long-chain tetraalkylammonium cations are the sum of the partial reactivities of C-H bonds at different positions in the molecules, indicating that the reaction of OH radicals with these cations involves the abstraction of H atoms in the rate-determining step. The partial reactivity for hydrogen abstraction from carbon atoms adjacent to the nitrogen center is nearly two orders of magnitude less than for comparable groups in aliphatic hydrocarbons. Influence of the nitrogen center extends even to the ..beta..more » position where partial rate constants are a factor approx. 5 less.« less