In this study, starch-based microparticles (MPs) fabricated by a water-in-water (w/w) emulsificationcrosslinking method could be used as a controlled release delivery vehicle for food bioactives. Due to the processing route without the use of toxic organic solvents, it is expected that these microparticles can be used as delivery vehicles for controlled release of food bioactives. Octenyl succinic anhydride (OSA) starch was used as raw material. Optical microscopy showed OSA starch-based microparticles (OSA-MPs) had a good dispersibility. Scanning electron microscopy (SEM) showed OSA-MPs had a solid structure and spherical shape. X-ray diffraction (XRD) patterns revealed that OSA-MPs were of amorphous structure. A Placketta??Burman screening design methodology was employed to evaluate the effects of the process and formulation parameters on the particle size of OSA-MPs. Considering the statistical analysis of the results, it appeared that the OSA starch concentration (P = 0.0146), poly(ethylene glycol) (PEG) molecular weight (P = 0.0155), volume ratio of dispersed phase/continuous phase (P = 0.0204) and PEG concentration (P = 0.0230) had significant effect on particle size.