Iron(III) hexacyanoferrate(II), Fe-4(III)[Fe-II(CN)(6)](3), has been used to modify the LiMn2O4 (LMO) cathodes for improving the high rate performances of lithium ion batteries. Iron(M) hexacyanoferrate(II) is a mixed valence compound with electronic and ionic conductivity, which differs from conventional inert modification materials for LMO cathodes. Both thin film and powder type cathodes have been investigated. The modified LMO cathodes can be discharged at high C-rates and still deliver applicable capacities, which satisfies the requirement of electric vehicles. The enhanced high rate performances can be attributed to the reduced interface charge transfer resistances due to iron(III) hexacyanoferrate(II) modification, as measured by the electrochemical impedance spectra. (C) 2013 The Electrochemical Society.