A new two-step solid-state process was developed for synthesis of a pure phase 4.7V LiMn1.5Ni0.5O4−δ (LMNO) spinel of good electrochemical properties. This process which was based on formation of stable Ni1−x Mn2O4−δ (x ≤0.33) spinel followed by subsequent lithiation, demonstrated the emerging of LiMn1.5Ni0.5O4−δ frame work at temperatures of as low as 350°C. During this lithiation process, migration of metal ions (Ni/Mn) from partially occupied tetrahedral 8a sites (in Ni0.67Mn2O4−δ ) toward octahedral 16d site occurred. The resultant spinel material displayed low irreversible loss, a 97% columbic efficiency and 6% loss in discharge capacity after 100 cycles at 60°C.