Gel permeation chromatography has been applied to iodine scavenging studies of the distribution of radicals produced in the radiolysis of symmetrically branched hydrocarbons 2,3-dimethylbutane, 2,4-dimethylpentane, and 3-ethylpentane. The principal iodides observed are those expected as a result of simple bond rupture. In the case of 2,3-dimethylbutane all five expected iodides are readily resolvable and it is shown that the loss of H from a tertiary position is favored over loss from a primary position by a factor of similar to10. A similar ratio is also observed for 2,4-dimethylpentane. The higher ratio of 15 observed for 3-ethylpentane indicates a dependence on the number of tertiary sites on the alkane. The relative yield of similar to3.3 for the loss of secondary and primary H atoms from 2,4-dimethylpentane and 3-ethylpentane is similar to that for normal alkanes, indicating a negligible effect of the adjacent tertiary carbon. In all three cases the rupture of terminal C-C bonds is relatively infrequent with C-C rupture occurring preferentially at the bonds adjacent to the tertiary carbon.