Rate constants for the reaction of OH radicals and Cl atoms with a series of n-alkyl nitrates have been determined at 295 ± 3K and a total pressure of approximately 1 atm. The OH rate data were obtained using both the absolute rate technique of pulse radiolysis combined with kinetic spectroscopy and a conventional relative rate method. Chlorine atom rate constants were measured using only the relative rate method. The results of the present study indicate that at atmospheric pressure rate data for the reaction of OH radicals with alkyl nitrates from both direct and relative rate experiments are in good agreement. The data show that the nitrate group substantially decreases the rate constant for H atom abstraction from groups bonded to the -ONO₂ groups and also decrease those for groups in the B position. -from Authors