A new variety of LiMnO 2 exhibiting a layered structure has been obtained by chimie douce reaction from α-NaMnO 2 . This material crystallises in the monoclinic system. Rietveld refinement of the X-ray diffraction pattern shows clearly that the MnO 6 octahedra are strongly distorted, as the result of the Jahn-Teller effect on the trivalent manganese ions. Moreover, a small amount of manganese is present within the lithium layer, contrary to the α-NaMnO 2 precursor phase which exhibits a strictly bidimensional structure.