An examination has been conducted of the oxidation of iso-butylene and an iso-butylene/n-octane mixture at 1080 K and one atmosphere. It was found that the addition of iso-butylene to n-octane results in a delay in the formation of CO and CO2even ifenough additional O2is added to maintain a n overall equivalence ratio of one. Analysis of the oxidation of iso-butylene alone suggests that the inhibiting effect of iso-butylene addition results from a reduction in radical concentrations due to the abstraction reactions of the radicals with the iso-butylene to yield unreactive methyl radicaland allene.