The aim of the present study was to verify that a whey protein-based layer can improve oxygen barrier properties of commercial compostable plastic film, while not hindering the biodegradability of the compostable film as well as not affecting the quality of the compost. The whey protein-based coating was applied on a biodegradable commercial film certified to meet the requirements of EN13432. Oxygen barrier properties were significantly improved by the presence of the whey protein layer. This result is particularly important since biodegradable packaging generally lack in maintaining barrier properties and the use of not degradable materials to improve barrier to gas and water vapour compromises the composting of the final packaging. In addition to that, it was important to assess the biodegradability of the whey protein layer itself since natural polymers may became not degradable if cross-linked or blended with not degradable additives. The material based on denatured whey protein and plasticizer presented fast biodegradability even after application on the commercial film. These positive results have potential to be used in new cost effective and ecological food packaging designs. (C) 2014 Published by Elsevier Ltd.