A new polymorph of lithium manganese pyrophosphate was synthesized by low-temperature solid-state synthesis, and the crystal structure was determined. The new phase has a new type of three-dimensional framework structure, which is completely different from that found in the previous study by Adam et al., J. Solid State Chem., 2008, 181, 3110. Electrochemical measurement with a Li cell demonstrated a reversible electrochemical activity at around 4 V.