1-Hydroxy-2-Bromo-3-Allyloxypropane (allyl glycidyl ether bromohydrin) and 1-hydroxy-2-bromo-3-allyloxypropane phosphoric acid ester (allyl glycidyl ether bromophosphate), which are useful as polymerizable flame-retardants, are described. 1-Hydroxy-2-bromo-3-allyloxypropane was prepared by the reaction of equimolar amounts of allyl glycidyl ether and hydrobromic acid, in acetic acid, preferably at a temperature in the range of 25.degree.-50.degree. C. and the thus obtained allyl glycidyl ether bromohydrin was phosphated by reaction with a substantially equimolar amount of polyphosphoric acid, preferably at a temperature in the range of about 40.degree.-50.degree. C., to produce the 1-hydroxy-2-bromo-3-allyloxypropane phosphoric acid ester.