AbstractThe metastable molecular ion of 2‐hexanone loses a methyl radical mainly (∼80%) from positions C(4) and C(6), in equal proportions, as indicated by 13C labelling. The necessary skeletal rearrangement of the butyl chain is interpreted in terms of a 1,2‐[enol‐olefin] +˙ shift. The results and the mechanisms concerning the minor eliminations of C2H4, C2H5˙, C3H5˙ and C3H6 neutrals are also discussed.