The rate constants for the reaction of NO with a series of peroxy radicals: CH₃O₂, C₂H₅O₂, (CH₃)₃CCH₂O₂, (CH₃)₃CC(CH₃)₂CH₂ O₂, CH₂FO₂, CH₂ClO₂, CH₂BrO₂, CHF₂O₂, CF₂ClO₂, CHF₂CF₂O₂, CF₃CF₂O₂, CFCl₂CH₂O₂ and CF₂ClCH₂O₂ were measured at 298 K and a total pressure of 1 atm. The rate constants were obtained using the absolute technique of pulse radiolysis combined with time-resolved UVVIS spectroscopy. The results are discussed in terms of reactivity trends and the atmospheric chemistry of peroxy radicals.