Abstract: A variety of theories have been proposed regarding the mechanism of strand scission following an oxidative event in duplex DNA, though none thus far provides a unifying mechanism of strand cleavage. Several studies appear to point to the formation of a one-electron oxidized guanine-cytosine pair (G•+/C) as an intermediate to oxidative cleavage, and while theory suggests strongly that this should be the most important primary intermediate, only indirect evidence for its existence in any regard have been reported. This work undertook a computational characterization by Density Functional Theory (DFT) of the G•+/C pair, and examination of its thermodynamic and kinetic behavior in order to determine to what extent it (and more importantly, its proton-transfer product G •/C+) might participate as an intermediate in scission reactions. Computational data revealed that while the G•/C+ pair formation from G•+/C was endothermic in gas phase, transfer was exothermic in water and dichloromethane solvent models (-0.871 kcal/mol and -0.584 kcal/mol respectively). Further, kinetic barriers in each case were sufficient to largely preclude the reverse reaction, making interconversion rate-limiting in both solvent environments. Computational data on the one-electron oxidized adenine-thymine (A•+/T) pair suggested while proton transfer was endothermic in both gas and solvent phases, kinetics were on a similar time scale to other charge transport mechanisms, suggesting that a full description of charge migration in DNA must take proton transfer for both purine radical cations into account. These results suggest strongly that the G•+/C+ system is likely a major contributor to DNA cleavage mechanisms, and that barriers to interconversion between proton transfer forms likely compete with other charge transport processes.