Aryl radical anions created in liquid alcohols decay on the microsecond time scale by transfer of protons from the solvent.(1,2) This paper reports a 4.5 decade range of rate constants for proton transfer from a single weak acid, ethanol, to a series of unsubstituted aryl radical anions, Ar-center dot. The rate constants correlate with free energy change, Delta G degrees, despite wide variations in the two factors that contribute to Delta G degrees: (a) the reduction potentials of the aryls and (b) the Ar-H-center dot bond strengths in the product radicals. For aryl radical anions containing CH2OH substituents, such as 2,2'-biphenyldimethanol(center dot-) which is protonated with a rate constant of 3 x 10(9) s(-1), the faster rates do not fit well in the free energy correlation, suggesting a change in mechanism.