The mechanistic analysis pertaining to the reductive cleavage of C-X (X=Cl, Br, I) bonds in halopentafluorobenzenes has been investigated at glassy carbon electrodes using convolution potential sweep voltammetry. The quadratic activation-driving force relation has been found valid, with potential-dependent transfer coefficients. The charge density analysis using density functional calculations, estimation of intrinsic barriers, and standard reduction potentials indicate that the mechanism cannot be classified unambiguously either as stepwise or concerted in these compounds. From various diagnostic criteria, the C-X bond cleavage mechanism appears to be borderline between stepwise and concerted. © 2008 The Electrochemical Society.