Abstract This study investigates the penetrant transport properties of water, oxygen, and carbon dioxide at 35 °C in poly(ethylene 2,5-furanoate) (PEF) isothermally crystallized at 115 and 160 °C. Dual-mode analysis of the water sorption isotherms for the semicrystalline vs. amorphous PEF samples indicates that the Henry’s law sorption parameter ( k D ) is reduced for the semicrystalline samples in direct proportion to the volume fraction crystallinity measured via both density and thermal methods. While the k D for water obeys the simple two-phase model of crystallinity, an unexpected large reduction in the Langmuir capacity constant ( C H ′) for the semicrystalline vs. amorphous samples resulted in an overall reduction in water sorption capacity greater than predicted by the two-phase model. Corroboration of this behavior for water is provided by independent oxygen and carbon dioxide permeation and sorption measurements, which also exhibit larger than expected reductions in solubility for the semicrystalline vs. amorphous samples. This study, which complements prior work, provides an initial look into the effect of crystallinity and morphology on the penetrant transport properties of PEF.