The shiftδTof the selective reflection temperature due to an exposure to γ-rays is studied for a mixture of cholesteric substances dissolved in various organic solvents. Values ofδTsuch as 0.2°C per krad can be obtained. The influence of the solvent nature (carbon tetrachloride, chloroform, trichloroethylene, …) is also discussed. It is shown that the shiftδTis due to the presence of radiolysis products of the solvent; this effect is more specially studied in the case of carbon tetrachloride containing a radical scavenger.