Abstract: Novel brominated polydiisopropylarylene compounds which can be used for imparting fire retardance properties to polymers such as polystyrene and polypropylene contain bromine as a substituent on the aliphatic radicals and have the following formula: ##STR1## A is a thienylene group or an arylene group such as a substituted or unsubstituted phenylene, biphenylene, napthylene, or anthracylene group, R.sub.1 through R.sub.4 a methyl group substituted or not with bromine, R.sub.5 and R.sub.6 a bromine atom or a hydrogen atom, and n a whole number in the range of 2 to 10, the number of bromine atoms per molecule in the aliphatic groups being at least 2 and the total bromine content being not more than 70 per cent by weight.