Dinitroaromatics have a long scientific history, with very recent (e.g. S.F. Nelsen, M.N. Weaver and J.P. Telo, J. Phys. Chem. A 113, 7730 (2009)) important contributions. The electron affinities for the nitrobenzene, dinitrobenzene and dinitronaphthalene isomers are predicted. The ten obvious structures of neutral dinitronaphthalene (DNN) have been predicted from theory. These ten isomers span an energetic range of 14 kcal mol-1, with the global minimum 2,7 structure lying only 0.3 kcal mol-1 below 2,6. The analogous ten isomers of the DNN radical anion have also been optimized and display a broader range of 25 kcal mol-1. Among the anions 2,6-DNN lies below the next most favourable isomer (2,7) by 6.5 kcal mol-1. The three known adiabatic electron affinities are predicted to be 1.12 (nitrobenzene), 1.91 (ortho-dinitrobenzene), 1.94 (meta-dinitrobenzene), and 2.32 eV (para-dinitrobenzene), values that range from 0.12 to 0.32 eV above the most recent experiments. We conclude that the experimental vertical detachment energy (VDE) of 3.10 eV for para-dinitrobenzene is too high by a surprising 0.85 eV. For the dinitronaphthalenes the following adiabatic electron affinities are estimated; 1.70 (1,2-dinitronaphtalene), 1.81 (1,3), 2.12 (1,4), 1.85 (1,5), 1.78 (1,6), 1.86 (1,7), 1.47 (1,8), 1.53 (2,3), 1.99 (2,6), and 1.69 eV (2,7).