Moisture migration through PKO based films under vapor-induced and liquid-induced conditions were investigated through measurements of unsteady state diffusivity, steady state permeability, and characterization of structure. A model was developed to describe changes in diffusivity through fat-based films containing hydrophilic components. At water activity gradients of 0.80 and 0.90, there were no significant differences in diffusivity and permeability values of PKO based films containing sucrose under vapor-induced and liquid-induced conditions. Addition of sucrose decreased both diffusivity and permeability of the films at a water activity gradient of 0.80. However, at a water activity gradient of 0.90, addition of sucrose increased permeability. At a water activity gradient of 1.0, diffusivity and permeability were significantly higher in sucrose containing films at liquid-induced condition than at vapor-induced condition. Addition of sucrose at a water activity gradient of 1.0 significantly reduced diffusivity but increased permeability under both vapor-induced and liquid-induced conditions. There were no significant differences in diffusivity and permeability of the film containing lecithin or cellulose under liquid-induced and vapor-induced conditions at a water activity gradient of 1.0. Addition of lecithin or Cellulose significantly reduced diffusivity but increased permeability. (C) Published by Elsevier Ltd.