Their transformation into foam-like structures would decrease their density, but may at the same time improve their specific mechanical properties, hence reducing materials costs. The associated processing routes should clearly involve neither emission of volatile organic compounds (VOCs) nor production of ozone depleting or greenhouse gases. The present work focuses on the development of PLA/MFC biocomposites considering a novel compounding technique and the use of supercritical carbon dioxide (CO2) to produce PLA/MFC foams. CO2 is a non-toxic, non-flammable, chemically inert, inexpensive and abundant gas, readily available directly from the atmosphere or as a by-product from industrial processes such as ammonia and ethanol production.13 Moreover, as physical foaming is used throughout, no additional CO2 is directly generated during the foaming process.