A Hammett-type correlation pertaining to the cleavage of radical anions of aromatic halides has been formulated. The expression has been verified using the reaction series of aromatic chlorides and bromides. The correlation reveals the sensitive nature of the carbon-chlorine bond to the polar effects of the substituents in comparison to the carbon-bromine bond. The cleavage rate constants of radical anions of some aromatic chlorides and bromides have been deduced using the correlation. The standard potentials for formation of radical anions of aromatic chlorides and bromides have been estimated based on the correlation. © 2005 Elsevier Ltd. All rights reserved.