A process for preparing a polybrominated product such as decabromodiphenyl ether and decabromodiphenyl ethane, which comprises brominating a reduced particle size precursor of said polybrominated product in an organic solvent or in bromine as a solvent, wherein the bromination is carried out either concurrently with or subsequent to said particle size reduction, forming the polybrominated product and separating the same from the reaction mixture.