Abstract: An encapsulated flame retardant is made by a process including applying an organic silicon composition to a powder flame retardant. The organic silicon composition is an organofunctional-silane or a mixture of organofunctional silanes, an oligomeric organosiloxane or a mixture of oligomeric organosiloxanes, or a solvent-containing preparation based on monomeric organosilanes and/or on oligomeric organosiloxanes, or a preparation based on water-soluble organopolysiloxanes, or mixtures of any or all of these. These surface-modified flame retardants are used in particular in polymers and polymer compounds, for rendering naturally occurring materials flame retardant, and also for the intumescent coating of combustible materials.