Addition of biomass-based ESO as a novel plasticizer in EC resulted in better film performances than conventional EC films with or without other commercial plasticizers. The tensile strength, elastic modulus, elongation, folding endurance and bursting strength of ESO–EC films were similar to or even better than those of corresponding DBP–EC and TEC–EC films, especially for ESO-15. ESO–EC films showed good thermal stability and non- flammability. Meanwhile, ESO decreased the Tg from 124◦C (pure EC film) to 71◦C (ESO-25), which could facilitate the processing of films. ESO reduced the oxygen and water vapor permeabilities of EC films as a result of its hydrophobic nature and the compact structure of ESO–EC films. In summary, ESO–EC film, which is com- pletely biomass-derived material, has great potential to substitute conventional plasticized films in various fields.