the present disclosure relates to an inorganic , halogen - free flameproofing agent made of modified , rehydrated red mud , having a mineral composition of 10 to 50 weight percent of iron compounds , 12 to 35 weight percent of aluminum compounds , 5 to 17 weight percent of silicon compounds , 2 to 21 weight percent of tio 2 , and 0 . 5 to 6 weight percent of calcium compounds , wherein the compounds of iron have a hydroxide and oxide hydrate fraction greater than or equal to 50 weight percent relative to the oxide fraction of the iron compounds , and wherein the compounds of aluminum have a hydroxide and oxide hydrate fraction greater than or equal to 50 weight percent . the disclosure further relates to a flameproofed material system comprising a flammable material and the inorganic , halogen - free flameproofing agent and to a method for the production thereof .