The study of the competitive unimolecular decomposition of chemically activated alkyl radicals is extended to cases of rupture of a propyl fragment vs a methyl or ethyl fragment. A study of the decomposition at room temperature of the octyl-4, heptyl-3, and 3-methyl-hexyl-2 radicals, formed by addition of H atoms to trans-octene-4, trans-heptene-3, and 3-methylhexene-1, is reported. The value of D0° (n-Pr-H) is deduced to be within -0.8 kcal of the value of D0° (Et-H). Comparison of the results are made with values obtained on a theoretical model for the absolute and relative rates; good agreement was found.