PURPOSE: To enhance product yield, by controlling the excess bromine in the reaction of bromine with cyclododecatriene.

CONSTITUTION: Initial and additional amounts of bromnine and cyclododecatriene are controlled in such a way that a reaction mass is substantially free of sub- brominated and non-brominated cyclododecatriene, wherein a certain amount of cyclododecatriene and a certain amount of bromine are mixed in a reaction medium to form and maintain a reaction mass which is substantially free of sub-brominated cyclododecatriene. The reaction mass comprises (i) a solvent medium in which bromine, cyclododecatriene, hydrogen bromide and brominated species of the components of the solvent media are substantially soluble; (ii) hexabromocyclododecane, (iii) 0-1% by weight sub-brominated and non- brominated cyclododecatriene relative to the hexabromocyclododecane, (iv) about 0.3-10% by weight hydrogen bromide relative to the hexabromocyclododecane, (v) about 0-10% by weight brominated solvent species relative to the hexabromocyclododecane and (vi) free bromine.