AbstractVapour phase thermolysis at 485°C of methallyl acetate and the allyl esters of benzoic, phenylacetic and trifluoroacetic acid proceeds by radical mechanisms analogous to that proposed for allyl acetate1. Rates of primary allyl‐oxygen homolysis appear to depend only slightly on the nature of the acyl moiety.The induced radical decomposition proceeds mainly by addition to ester, followed by β‐elimination, polymerization being unimportant under the present experimental conditions.An explanation is offered for the fact that allyl(ic) esters of aromatic acids ‐ in contrast to those of aliphatic acids ‐ produce a substantial amount of carboxylic acid in addition to the main oxygen‐containing product, car