Abstract: We used the density functional theory at UB3LYP/6-31G(d) level, to study the process of bromine substituting for hydrogen on the benze ne ring. From the results of the calculations, it is a multistep reaction including a transition state and two intermediate states. A positive charge of Br⁺ transfers to H by means of intermediate ［C₆H₆Br］⁺. In fact, it is a process of electron transfer.

Key words: density functional theory, B3LYP, bromine reaction, el ectron transfer