The vapour sorption of three fluorocarbon fluids (tetrafluoroethane, chlorotetrafluoroethane, and heptafluoropropane) has been measured in crosslinked and uncrosslinked poly(dimethylsiloxane) as a function of the temperature in the interval 35-105 degrees C. For a given solvent, the swelling activity parameter, S, for the solvent/crosslinked polymer system decreases as both the degree of swelling and the temperature increase. The range of experimental conditions examined allowed consideration of S for different solvents, but constant molar volume, V-1. Plots of S as a function of degree of swelling can be reduced to families of curves at constant V-1 for the three solvents studied here. The dependence of S on solvent quality and temperature is then encompassed in its variation with V-1.