A method for the preparation of smooth and spherical microspheres of the hydrophobic corn protein, zein, by a phase separation method, is reported in this thesis. Solubility studies on zein as well as amino acid and peptide composition analyses, together with studies on the formulation process were carried out to comprehend the mechanisms of zein microsphere formation. Microspheres were characterised in terms of guest molecule loading, size, charge, morphology, and composition. Ovalbumin, as a model protein/antigen guest, was incorporated into the zein microspheres during microsphere formation at different experimental loadings, and its in vitro release was examined in phosphate buffer at 37 °C. Microsphere degradation studies as a function of medium pH and in the presence of enzymes were also performed in vitro to understand the release of the guest molecule. Zein microspheres were found to be extremely resistant to degradation in the absence of enzymes, which was reflected in negligible release of ovalbumin. Finally, zein microspheres (both blank and ovalbumin-loaded) were administered orally, intramuscularly, rectally, and vaginally to investigate whether a zein microparticulate carrier system was capable to induce an enhanced immune response to the model antigen. In these studies, adjuvanticity of zein microspheres could not be proved due to the antigenicity of the zein protein.