The C-N dissociation energies of the radical anions of nitrobenzene and all three nitrotoluene isomers were determined by measuring the appearance energy of the NO2 fragment from collision induced dissociation in a tandem mass spectrometer. The dissociation energy of nitrobenzene radical anion is 1.99+/-0.16 eV, o-nitrotoluene radical anion is 1.91+/-0.14 eV, m-nitrotoluene radical anion is 2.01+/-0.17, and p-nitrotoluene radical anion is 2.06+/-0.21 eV. All anion bond energies are lower than the neutral C-N bond energies by at least 1 eV. (C) 2013 Elsevier B.V. All rights reserved.