A reactive fire retardant mixture useful in the preparation of polyurethane foams. The mixture contains a halogenated imide-containing polyol having the formula: ##STR1## and the corresponding ether having the formula: ##STR2## wherein R is a hydrocarbon group having the valance n+2 and is selected from the group consisting of benzene groups, naphthalene groups and alicyclic hydrocarbon groups containing 5 to 10 carbon atoms, R' is an aliphatic hydrocarbon group containing 3-12 carbon atoms, X is selected from the group consisting of bromine and chlorine, n is an integer from 1-6 and p is an integer from 2-6. They are prepared by reacting an alcohol (e.g. isopropyl alcohol), a halogenated dicarboxylic anhydride (e.g. tetrabromophthalic anhydride) and an aminopolyol (e.g. 2-amino-2-ethyl-1,3-propanediol).