Freeze-drying method was employed in order to synthesize a LiFePO4/C composite. This method produced phosphate nanoparticles (10-20 nm size) covered in a carbon network. Nanostructuring and homogeneous conductive web around the active material promoted a good electrochemical response, with 141 mAh.g(-1) at C/1 and a capacity retention of 90% up to 300 cycles. However, XRD measurements showed the presence of an approximately 30% of a near heterosite Li0.1FePO4 intermediate phase in the initial sample, as a product of atmospheric aging. EPR spectrum displayed a very broad signal attributed to a high spin Fe3+ ion magnetically coupled to Fe2+, confirming the formation of the non stoichiometric LixFePO4 compound. Electrochemical measurements indicated the presence of active Fe3+ in the initial composite, in a structural environment close to that of a FePO4 heterosite system. A post-mortem cathode, stopped at 4 V, was characterized. Metastable LixFePO4 solid solution type phase was not noticed. Thus, it would have disappeared during cathode cycling life, and all active material would have evolved to a classic biphasic system. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3611435] All rights reserved.