The temperature dependence of the argon permeability and diffusion coefficients in poly(vinyl fluoride) and poly(vinylidene fluoride) was determined experimentally. Two transitions were revealed as slope discontinuities in the Arrhenius plots of the transport parameters for argon in poly(vinyl fluoride). Only one transition however was observed in poly(vinylidene fluoride). A transition at 40°C reported in the literature was not observed, a third transition which has been reported by use of other techniques was below −30°C, the lowest temperature conveniently obtained in the existing experimental apparatus. The results found are consistent with dilatometry data also reported in this paper and with literature values.