Foaming studies on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were performed to evaluate the potential impact of nitrogen gas solubility on foam microstructure and properties. It was found that there was a step change from low to high cell density below and above a specific pressure threshold. This pressure threshold, which is associated with nitrogen gas solubility in PHBV, was calculated in order to inform processing requirements for extrusion foaming of PHBV. In the process, the PVT properties of PHBV were also calculated to account for polymer swelling at high temperature and pressure. To validate the predictive method applied in this work, gas solubility of nitrogen was also determined for polypropylene (PP) and poly(lactic acid) (PLA), which have similar thermal and rheological properties to PHBV. Predicted PVT properties for PP were found to be similar to experimental values in the literature, with the predicted solubility having a 10-14% error for PP and 20-24% error for PLA. Application of the same error range to the solubility predicted for PHBV aligned well with experimental observations. POLYM. ENG. SCI., 54:2683-2695, 2014. (C) 2013 Society of Plastics Engineers