This study evaluated the oxygen permeability (O.P.) of starch‐sorbitol‐water films produced by casting. With a sorbitol content <20%, O.P. (0.15 10−16 cm2/s.Pa for 8.8% sorbitol) was lower than for other polymers classically used as oxygen barriers. With a sorbitol content >20%, O.P. (1.6 10−16 cm2/s.Pa for 24.9% sorbitol) was higher than for starch films without a plasticizer. These results were correlated with molecular mobility as determined by time‐domain NMR. Low and high O.P. corresponded respectively to a decrease and an increase of molecular mobility relative to sorbitol content.