The absorption of oxygen into the aqueous phase was measured in the presence of a dispersed silicone oil phase. In the most experiments, a thin, permeable membrane layer resulting from interface polymerization encapsulated the organic droplets. The size distribution and average droplet size, obtained at different stirrer speeds, were measured. Using a heterogeneous, multilayer mass-transfer model, enhancement was predicted as a function of mass-transfer coefficient without particles and average particle size. Enhancements measured and predicted were compared to each other as a function of the dispersed-phase hold-up and the average particle size. It was concluded that the particle size distribution can significantly alter the absorption rate; thus, its effect should take into consideration in the prediction of absorption rate enhancement.