Electrochemical studies of three types of CFx (F - fiber based, C - petroleum coke based, G - graphite based) have demonstrated different electrochemical performances in previous work, with fiber based CFx delivering superior performance over those based on petroleum coke and graphite. C-13 and F-19 MAS (magic angle spinning) NMR techniques are employed to identify the atomic/molecular structural factors that might account for differences in electrochemical performance among the different types of CFx. Small quantitative variations of covalent CF and LiF are noted as a function of discharge and sp(3) bonded carbons are detected in discharged F type of CFx. (C) 2011 Elsevier B.V. All rights reserved.