A process for flameproofing plastics comprising incorporating in the plastic a homogeneous granulate containing pulverulent red phosphorus with a particle size of up to about 100 microns and a binder; the granulate is more particularly comprised of a blend of10-97% by weight of red phosphorus,3-50% by weight of a binder melting between about 30.degree. and 180.degree. C. and being selected from waxes and/or waxy substances and/or metal soaps, and up to 87% by weight of addends promoting the flameproofing efficiency of the granulate, inhibiting the evolution of gaseous phosphines upon the incorporation of the granulate with the plastics, or being suitable fillers.