Summary: The objectives of this work were to produce expanded nanocomposites based on cassava starch, polyvinyl alcohol (PVA) and sodium montmorillonite (Na-MMT). The nanocomposites were characterized according to their expansion index (EI), density, water absorption capacity (WAC), mechanical properties and crystallinity. The nanocomposites were prepared in a single-screw extruder using different starch contents (97.6–55.2 g/100 g formulation), PVA (0–40 g/100 g formulation) and Na-MMT (0–4.8 g/100 g formulation). Glycerol (20 g/100 g formulation) was used as plasticizer. The addition of Na-MMT and PVA resulted in an increase of EI and mechanical strength of the foams. Na-MMT and PVA addition resulted in less WAC of the samples. The studied processing conditions resulted in a good nanoclay dispersion, leading to the formation of an intercalated structure.