Self-extinguishing polymeric compositions are taught comprising, expressed in % by weight referrred to the total composition:a) from 1 to 25% of at least an organic aliphatic, cycloaliphatic, aromatic halogen-derivative;b) from 10 to 40% of at least an adduct between an inorganic halide and a zeolite;c) from 0.5 to 5% of an organic reactive agent capable of modifying the polymeric matrix at the combustion temperature, comprising at least an organic compound which generates radicals at said temperature and at least a cross-linking agent;d) the remaining part being composed of at least a thermoplastic polymer and/or copolymer.