Gravimetric sorption and IGC were used to measure the sorption and the diffusion of water and methanol in PVOH. The crystalline character of the polymer was controlled and stabilized by annealing in the presence of moisture prior to the gravimetric sorption measurement. The diffusion results obtained are analyzed with the Vrentas-Duda free-volume theory of diffusion. A purified polymer was required in order to measure the sorption and diffusion of methanol.