Li3MnO4 Mn(V) was synthesized from LiOH and LiMnO4, and characterized by gravimetric, X-ray, and XPS analysis. This precursor was used to improve the calcination time required for the low temperature solid state synthesis of highly oxidized spinels, Li2Mn4O8+x . TG calculations were used to show the effect of calcination conditions on phase purity. The effect of a second phase on cycling performance was evaluated.