The behavioral analysis of carrier materials in supercritical carbon dioxide (CO2) is important for particle formation applications. In this work, the behavior of modified starches (Hi-Cap 100, Purity Gum Ultra, and Fluidex) in supercritical CO2 at 15 MPa and 60 °C is studied. Morphology and size profile of starch particles before and after contact with supercritical CO2 and their solubility and volumetric expansion in supercritical CO2 are analyzed. Morphology and size profiles of starch particles show physical changes; Purity Gum Ultra and Fluidex particularly show incremental changes in particle size. Solubility values for Hi-Cap 100 and Purity Gum Ultra are 0.06 g/kg of CO2; for Fluidex it is 0.14 g/kg of CO2. No volumetric expansion of pure starches mixed with ethanol is visibly detected; alterations are observed only in starches mixed with hydrated ethanol. Although the starches are chemically modified, which gives them hydrophobicity, their interaction with supercritical CO2 is minimal.