The radical reactions in the liquid phase γ-radiolysis of propane have been studied from –130 to 35°C and compared with the gas-phase radiolysis at 35°C. Oxygen was used as a scavenger to separate thermal radical yields, and effects of phase and temperature on the radical yields were assessed. The gas-liquid phase change(a) decreases total decomposition by about 14 %,(b) increases disproportionation/combination (D/C) ratios for all radicals by 30 % and (c) decreases the isopropyl/n-propyl radical ratio. The decrease in liquid temperature (a) changes the predominant reaction of H atoms from abstraction from propane to addition to product propylene below –78°C at doses of 1 Mrad, (b) increases the D/C ratios by 31% and (c) decreases the isopropyl/n-propyl radical ratio. Dose effects were briefly studied; they are complex and cannot be explained by radical reactions alone.