Solid powder generating minus ion was microencapsulated by polystyrene with the drying-in-liquid method. In the microencapsulation, (R)-(+) limonene as the solvent for polystyrene and ethylene glycol as the continuous phase were adopted instead of the conventional organic solvent such as dichloromethane, benzene and toluene, and water, respectively. It was mainly investigated whether the solvents adopted here could be applied to the drying-in-liquid method or not and how the viscosity of the shell solution and the oil soluble surfactant affected the content of core material. The oil soluble surfactant made hydrophilic solid powder more hydrophobic and resulted in an increase of the content. Microcapsules containing solid powder could be prepared with the drying-in-liquid method using (R)-(+) limonene and ethylene glycol. An increase in the viscosity of the shell solution repressed the movement of solid powder particles in a droplet of the shell solution during the microencapsulation process and resulted in the higher content. (C) 2008 Wiley Periodicals, Inc.