Nanosized powders in the system LiMn2−xFexO4 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) have been synthesized by sol-gel technique using citric acid as chelating agent. The effect of Fe substitution on the structure and surface morphology of spinel LiMn2O4 has been examined by X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM) and Electrochemical characteristics. The materials for all the compositions except x = 0.6 exhibit a phase pure cubic spinel structure as evident from the XRD analyses. Doping with Fe increases the crystallinity in the materials and decreases the average particle size. The surface morphology of the synthesized particles is spherical and polygonal type. Average particle size lies in the range of 60 to 400 nm. Improved capacity retention in rechargeable 4 V Li/LiMn2-xFexO4 cells has been observed when a small amount of manganese in the spinel cathode is replaced with iron. The first discharge capacities of LiMn2−xFexO4 (x = 0.0, 0.1, 0.2, 0.3) in a voltage range of 3 V to 4.3 V decreases as the x increases, however, the cyclic performance improves.