The photochemical fate of polychlorinated dibenzo-p-dioxins, ubiquitous environmental pollutants, could be highly influenced by electron-donors such as triethylamine. Therefore, it is essential to have electron affinities of these species. We have performed density functional calculations for neutral and anion of dibenzo-p-dioxin (DD) to obtain the adiabatic electron affinity. We find that the order of D-2 and D-2h structures varies with the level of theory. The D-2h neutral DD undergoes inversion distortion into less symmetric D-2 anion upon electron attachment due to C-O-C bond cleavage. (c) 2005 Elsevier B.V. All rights reserved.