By means of pulse radiolysis the one-electron reduction potentials of twelve 4-substituted aniline radical cations and the pK(a) values of eight 4-substituted aniline radical cations have been determined. Both the potentials and the pK(a) values were shown to be linearly dependent on the Brown sigma(p)(+) values for the 4-substituents. The one-electron reduction potentials were also compared to previously reported electrochemically determined E(1/2) values resulting in good agreement between the two sets of data. By combining the one-electron reduction potentials and the pK(a) values the N-H bond dissociation energies of some 4-substituted anilines were calculated, also showing a linear substituent dependence. The absolute N-H bond dissociation energy of aniline found was close to a previously reported value.