Polylactic acid (PLA) represents probably one the most viable environmentally-sustainable alternative to petrochemical-based plastics. This paper reports the continuous processing of PLA foams with CO 2 as the blowing agent. Different operating conditions were tested for a commercial linear PLA and the obtained foams were characterized on the basis of porosity and thermal properties. Finally, foams with expansion ratio up to 95% were obtained. The importance of the operating temperatures was emphasized, what requires the use of high CO 2 fractions. Higher crystalline contents than the raw material can be obtained, this content being linked to the process conditions and thus to the porosity.