We present results from testing the hypothesis that there is a different reaction pathway for the electrochemical reduction of PC EC-based electrolytes at graphite electrodes with LiPF6 as the salt in common. We examined the reduction products formed using ex situ Fourier transform infrared (FTIR) spectroscopy in attenuated total reflection (ATR) geometry. The results show the pathway for reduction of PC leads nearly entirely to lithium carbonate as the solid product (and presumably propylene gas as the co-product) while EC follows a path producing a mixture of organic and inorganic compounds. Possible explanations for the difference in reaction pathway are discussed. (c) 2005 The Electrochemical Society. All rights reserved.