Macro-sized particles and seamless capsules were prepared in a liquid system with continuous flow. The effect of process parameters was studied on the capsule size and the wall thickness. The experimental data were successfully fitted with equations developed on the basis of force balances. Particle size was found to decrease with increasing dispersed phase velocity at high continuous phase velocity, but to increase with increasing dispersed velocity at low continuous phase velocity. In the case of capsule preparation, larger capsules were formed at higher flow rate of total dispersed phase over the whole range of continuous phase velocity, independently of the flow ratio of dispersed phases. Therefore, it was found possible to increase external and internal capsule diameters by increasing total dispersed flow rate and decreasing continuous phase velocity. Capsules with thicker walls were yielded by increasing the flow ratio of dispersed phases at constant total flow rate of dispersed phase.