The transient optical absorption bands (lambda(max) = 310, 350-500 nm, k = 5.6 x 10(9) dm(3) mol(-1) s(-1)) formed on pulse radiolysis of an acidic (HClO4 = 7.8 mol dm(-3)) aqueous solution of benzene are assigned to the solute radical cation formed on acid-catalyzed dehydration of the OH adduct. The solute radical cation is able to undergo an electron transfer reaction with Br- with a bimolecular rate constant of 8 x 10(9) dm(3) mol(-1) s(-1). On the other hand, the OH adduct (lambda(max) = 310 nm) was oxidized by Fe(CN)(6)(3-) with a bimolecular rate constant of 6.6 x 10(7) dm(3) mol(-1) s(-1). The radical cation of benzene is a strong one-electron oxidant with oxidation potential in the range 2.1-2.4 V vs NHE.