A modified oil-in-water emulsion process was developed to produce novel microporous hemi-spherical polycaprolactone (PCL) microparticles called “hemi-shells”. Through the addition of a porogen such as sodium bicarbonate into the PCL-dichloromethane oil phase and emulsification in an acidic polyvinyl alcohol aqueous phase, microporous hemi-shells formed as dichloromethane evaporated. Carbon dioxide gas evolution from the porogen reaction with the acidic aqueous phase created particles with an externally microporous shell and a large internal cavity. The hemi-shells were characterized by various methods, including scanning electron microscopy and optical microscopy which were specifically used to quantify the hemi-shell yield. The final number-average particle yield of the optimised manufacturing method for particle manufacture in the 50-200 micron size range was 84%. The number-average hemi-shell yield in the same size range was 41%. These novel microparticles have potential applications in tissue engineering and drug delivery / Dissertation (MEng)--University of Pretoria, 2011. / Chemical Engineering / unrestricted