Alginate microspheres were produced by emulsification/internal gelation of alginate sol dispersed within vegetable oil, Gelification was initiated within the alginate sol by a reduction in pH (7.5 to 6.5), releasing calcium from an insoluble complex. Smooth, spherical beads with the narrowest size dispersion were obtained when using low-guluronic-acid and low-viscosity alginate and a carbonate complex as the calcium vector. A more finely dispersed form of the complexed calcium within the alginate sol promotes a more homogeneous gelification. Microsphere mean diameters ranging from 50 mu m to 1000 mu m were obtained with standard deviations ranging from 35% to 45% of the mean.