Abstract: A process for the production of microspheres of thorium oxide, uranium oxide or plutonium oxide and mixtures thereof, containing carbon. The microspheres are prepared by first forming an aqueous alkaline solution of a salt of said metals which will precipitate to a solid form in a concentrated alkaline medium together with an alkaline polymerizable organic monomer and carbon, thereafter dripping this solution into a concentrated alkaline medium wherein metal hydroxide is precipitated out and said monomers polymerized to thereby form said microspheres. The precipitated metal compounds with polymerized monomer and carbon are washed to remove unwanted ions and dried by various methods such as air currents, infrared lamps, high frequency microwaves or preferably by azeotropic distillation whereby the washed particles are dispersed in an organic liquid immiscible with water which is then boiled off. Simple liquids include 1,1,1-trichloroethane, carbontetrachloride and xylene.