The 3.7 V peak observed in the cyclic voltammogram of LixMn2O4 was investigated using the in situ bending beam method and synchrotron X-ray diffraction (XRD). The cyclic voltammogram (CV) at different cutoff voltages revealed the 3.7 V peak during the anodic scan only when the sample was subjected to the 3 V range. The differential strain curves (d epsilon/dt) obtained simultaneously with the CV indicated the presence of tensile strain in the vicinity of 3.7 V suggesting sample volume contractions due to a phase transformation. Synchrotron XRD confirmed that the material underwent a tetragonal to cubic phase transformation. (c) 2006 The Electrochemical Society.