The spinel Li1.03Mn2O4 powders having submicron, narrow particle-size distribution, and excellent phase-pure particles have been synthesized at low temperatures from aqueous solution of metal acetate containing glycolic acid as a chelating agent by a sol-gel method. The dependence of the physicochemical properties of the spinel Li1.03Mn2O4 powders on the various calcination temperatures and glycolic acid quantity have been extensively studied. It was found that the physicochemical properties of the Li1.03Mn2O4 powders could be controlled by simply varying the pyrolysis processing and chelating agent quantity. The glycolic acid-assisted Li1.03Mn2O4 powders have shown excellent rechargeability and delivered discharge capacity of 134 mAh/g for more than 90 cycles in Li/polymer electrolyte/Li1.03Mn2O4 cells cycled between 3.0 and 4.3 V. The Li1.03Mn2O4 powders in Li/1 M LiBF4-EC/DEC electrolyte/Li1.03Mn2O4 cells cycled between 3.6 and 4.3 V retained 94% of its initial capacity over the 100th cycle.