Self-extinguishing styrene polymer particle foam

Self-extinguishing styrene polymer foam particles containing, in each case based on the styrene polymer, a) 0.05 to 0.2 wt .-% of an organic bromine compound having a bromine content of at least 70 wt .-% as flame retardant and b) from 0.1 to 2 wt .-% of a flame retardant synergist, as well as procedures for preparing expandable styrene polymers that are processible into self-extinguishing styrene polymer particle foam obtained by prefoaming and sintering using hot air or water vapor.