The anodic stability of anions is an important factor in determining the maximum operating voltage of lithium-ion cells, if appreciable degradation is to be avoided. A linear correlation was observed between the highest occupied molecular orbital energies calculated by ab initio molecular orbital theory [HF/6-31G(d), 6-31 + G(d,p), 6-311 + G(2d,p)] and the limiting oxidation potentials measured by linear sweep voltammetry, which supports experimental results that inorganic fluorine-containing anions are more resistant against oxidation than their organic counterparts: CF3SO3- < (CF3SO2)(2)N-, (CF3SO2)(3)C-, BF4- < PF6- < AsF6-. The ionization potentials of these anions were also calculated from the energy difference between the anion and the neutral radical by ab initio density functional theory [B3LYP/6-31G(d), 6-31 + G(d,p), 6-311 + G(2d,p)]. This high accuracy procedure explained the subtle energy difference between (CF3SO2)(2)N- and (CF3SO2)(3)C-.