Work in our group has shown a direct relationship between arene-cation binding enthalpies and the aromatic quadrupole moment (Theta(zz)); the more negative the Theta(zz) value, the greater the arene-cation binding enthalpy. The ability to predict aromatic Theta(zz) values from the aromatic substitution pattern would therefore allow for the simultaneous prediction of the arene-cation binding enthalpy. Substituent constants were developed for the accurate prediction of Theta(zz) values for mono-, di-, tri- and tetra-substituted aromatics. The Theta(zz) values predicted from the developed substituent constants perform very well in determining relative arene-cation binding enthalpies. (c) 2006 Elsevier B.V. All rights reserved.