AbstractPolymers of methyl, ethyl,n‐butyl,n‐octyl, andn‐cetyl acrylate were γ‐irradiatedin vacuo, and the effects of irradiation temperature (−196 to 56°C.) on energy yields for crosslinking and degradation estimated from gel fractions and swelling behavior of the gel. The extent of degradation is independent of polymer structure and reaction temperature, suggesting a molecular chain breaking process. Crosslinking, found to occur predominantly on the alkyl side chain, is independent of temperature above and below the polymer softening point, but is severalfold higher for irradiations above the softening point; these data seem to reflect the importance of segmental mobility of radiation produced polymer radicals in the crossl