Ring-substituted benzyl radicals exhibit electronic energies of the D-1 -> D-0 transition being shifted to red region with respect to the benzyl radical. The red-shifts of disubstituted benzyl radicals are highly dependent on the substitution positions irrespective of substituents. By analyzing the red-shifts of dichlorobenzyl radicals observed, we found that the substituent effect on electronic transition energy is attributed to the molecular plane shape of delocalized pi electrons. We will discuss the influences of locations of Cl substituents on the D-1 -> D-0 transition energies of dichlorobenzyl radicals using Mickel's molecular orbital theory. (C) 2015 Elsevier B.V. All rights reserved.