A series of spinel-structured LiMn2−x−y Ni x Cr y O4 have been prepared and their electrochemical performances as 5-V cathode materials for lithium ion batteries are evaluated. The synthesis reactions for these materials are characterized by TG/DSC, XRD and SEM. TG/DSC measurements show that the chemical reactions for the final product are completed below 400°C. XRD analysis indicates that spinel structure is formed at around 650°C. However, SEM images show well-defined polyhedron crystalline particles do not appear until 800°C. Electrochemical evaluation shows that LiMn1.4Ni0.4Cr0.2O4 prepared at 850°C boasts the best electrochemical performance with an initial discharge capacity of 128mAh/g and a capacity retention of more than 90% after 230 cycles between 3.5 and 4.98V.