Radiation induced dehalogenation of haloarenes and binding of arenes have been studied in polyolefin films. Dehalogenation takes place from a highly excited triplet state that is formed by the recombination of arene radical ions, while binding takes place through a polymer aryl radical intermediate. The latter process is dependent on the reactivity of the polymer radical and decreases in low molecular weight and branched polymer films. It is found that energy deposited by high-energy irradiation is transferred efficiently out of the crystalline zones and into the amorphous zones of the polymer.