Uniform microspheres substantially or completely free from internal cavities and voids are prepared by spraying an aqueous hydrated metal oxide solution onto the surface of a water-immiscible organic liquid containing from 0.04 to 2.0 percent by volume of a surface active agent, the viscosities of each of the organic and inorganic phases plus the amount of surface active agent within the above range being selected such that there is sufficient surface active agent present to prevent the globules from adhering to each other yet an insufficient amount to prevent deformation from the substantially spherical shape.