A solid-state reaction to synthesize a lithium multi-transition metal phosphate LiCo1/3Mn1/3Fe1/3PO4 is used in this work, which has a high voltage of 3.72V and capacity of 140mAhg−1 at a 0.05C rate. From the in-situ XRD analysis, LiCo1/3Mn1/3Fe1/3PO4 has shown a high stability during cell charge/discharge, even operating at 5V, which is due to the stable olivine structure. Although all the transition metals Co2+, Mn2+ and Fe2+ are at the same 4c site of the LiCo1/3Mn1/3Fe1/3PO4 structure, they seem to have different chemical activities and reflect on the electrochemical performance. The capacity contributed by the Co2+/Co3+ redox couple is only 20mAhg−1, which is less than that of the Fe2+/Fe3+ and Mn2+/Mn3+ redox couples. This is because of the fact that the diffusivity of lithium ion for the Co2+/Co3+ redox couple is 10−16 cm2 s−1 which is one order less than that of the Fe2+/Fe3+ and Mn2+/Mn3+ redox couples in LiCo1/3Mn1/3Fe1/3PO4.