The preparation and characterization of spinel LiMn2O4 have been studied. Spinel lithium manganese oxides are prepared by a sol–gel method using LiNO3 and Mn(CH3COO)2 ·4H2O as starting materials in which the obtained gel is heated at various temperatures after pretreatment at 350°C or without pretreatment in air. The LiMn2O4 samples prepared with pretreatment have uniform microsized particles while those obtained without pretreatment have agglomerated particles of irregular shapes. The thermal pretreatment at 350°C improves the electrochemical behaviour in terms of discharge capacity and rate capability. The results can be correlated with an increase in lithium surface reaction sites in these materials, as inferred by this small grain size and large surface area.