The effects of extrusion parameters on soy protein concentrate (SPC) and cassava starch blends were studied. Extruded samples were prepared by using a Werner and Pfleiderer twin-screw extruder. The study was carried out by using Response Surface Methodology. The highest values for axial expansion were found at the maximum SPC level in the blend and at the lowest feed moisture. Higher levels of SPC, greater than 25%, reduced radial expansion. The specific Volume increased as the SPC level in the blend increased and feed moisture decreased. The highest water absorption index (WAI) was found at the highest feed moisture and with the maximum SPC level in the blend, while decreasing the SPC level increased the water solubility index (WSI) of the extrudates.302189203