The calculations in this work update the chemistry of peroxy radicals formed in isobutanol oxidation using pressuredependent rates for all three peroxy radical isomers. We obtain general agreement with the potential energy surface proposed by Zádor et The three isomers in this work react through different channels. The fate of αR + O 2 almost entirely results in HO 2 + isobutanal, which agrees with the results of Zádor et al. The reaction of γR + O 2 almost entirely forms H 2 O and alkoxy at lower temperatures, as suggested by Welz et al., with a mixture of products at higher temperatures. The βnetwork predominately proceeds via the Waddington pathway at lower temperatures, though there is much more competition with other pathways at higher temperatures than other studies suggest. The rates from this work can explain the lack of two-stage ignition from isobutanol combustion.