Modified lithium manganese oxides were prepared by using LiMn 2 O 4 and LiCoO 2 as precursors by solid state reaction.A study has been carried out by TG - DSC,XRD and FTIR to analyze the reaction process and structural characterization of products.The results showed that the LiMn 2 O 4 reacted chemically with LiCoO 2 at high temper - ature.Li and Co atom could insert into the LiMn 2 O 4 crystal lattice and obtained the Cobalt - Doped spinel com - pound.The results of constant - current cyclic test showed that the cyclic stability of the products are increased with the amount of doped LiCoO 2 ,while their initial capacity is decreased.