Ultrafine spherical maltodextrin and maltose particles were successfully produced with the antisolvent vapour precipitation (AVP) technique. Comparison between the two materials confirmed that a key requirement for the process is in inhibiting crystallization of the material. The precipitation process consists of: (1) an initial phase separation forming an emulsion formation, (2) phase inversion and (3) finally a water-maltodextrin shrinkage phase which forms the spherical particles driven by interfacial surface tension. Dehydrating the droplet at different stages of the process resulted in various particle morphologies; porous, smooth, microsphere network and microspheres. Higher ethanol relative humidity, higher ethanol absolute humidity and lower initial weight concentration were found to favour the formation of amorphous microspherical particles upon drying.