Rate constants for the reaction of OH radicals and Cl atoms with CH₃ONO₂, C₂H₅ONO₂, n-C₃H₇ONO₂, n-C₄H₉ONO₂, and n-C₅H₁₁ONO₂ have been determined at 298 ± 2 K and a total pressure of approximately 1 atm. The OH rate data were obtained using both the absolute-rate technique or pulse radiolysis combined with kinetic spectroscopy and a conventional photolytic relative-rate method. The Cl rate constants were measured using only the relative-rate method. Evidence is presented from the kinetic studies that reaction of OH radicals with alkyl nitrates may involve both addition and abstraction pathways. The data show that the -ONO₂ group substantially decreases the rate constant for H-atom abstraction by OH radicals from groups bonded to the -ONO₂ group and also decreases that for groups in the β position. Similar resuls were found for the reaction of Cl atoms with these compounds. The results are discussed in terms of reactivity trends.