Bromide oxidation and bromine reduction were investigated at boron-doped diamond (BDD) electrodes, in acidic media. Both the anodic and the cathodic reactions of the bromine redox couple were found to take place through a mechanism in which the Volmer step is rate-determining, as a result of a very poor stabilization of intermediate radical species. Accordingly, exchange current densities at BDD and polycrystalline Pt differ by more than five orders of magnitude. Finally, from the analysis of CV data, estimations of the anodic and cathodic transfer coefficients, as well as of heterogeneous rate constants, were obtained.