The passivation and breakdown behavior of 1018 carbon steel in propylene carbonate (PC) or dimethoxyethane (DME) mixtures with water and containing 0.5M LiAsF6 were studied. The behavior of the steel in the organic solvent/water mixtures was highly dependent on the organic solvent. The anodic polarization of carbon steel displayed active-passive behavior in 10-90 mole percent (m/o) PC/H2O mixtures and a tenuous degree of stability within the passive range. The anodic polarization of carbon steel displayed no active-passive behavior in 50-90 m/o DME/H2O mixtures and displayed active-passive behavior in 10-30 m/o DME/H2O mixtures. The steel was stable within the passive range of these DME/H2O solutions. The breakdown potential of the steel in DME/H2O mixtures is more electropositive than the oxidation potential of the DME solvent at all molar ratios.