Abstract: Monomeric and polymeric halogenated organic compounds derived from 2,2',6,6'-tetrabromo-3,3',5,5' -tetraalkyl-4,4'-biphenols are described. The derivatives are useful in their monomeric and polymeric form as flame retardant additives and/or concentrates for normally flammable resinous materials. The thermal stability at elevated temperatures of the brominated biphenol derivatives advantageously benefits polymeric compositions containing the brominated biphenol derivatives especially when the polymeric compositions are molded into three dimensional articles, or formed into films, sheeting or shaped into fibers, laminates or reinforced plastics by conventional techniques.