Lithium manganese oxides, and in particular the spinel-structured LiMn 2 O 4 , have been investigated as potential active cathode materials for lithium ion batteries. Recently both orthorhombic and monoclinic LiMnO 2 have attracted considerable attention. It has been reported that Al doping allows the preparation of monoclinic LiAl x Mn 1-x O 2 under suitable reaction conditions, and furthermore improves the capacity retention of both o-LiAl x Mn 1-x O 2 and m-LiAl x Mn 1-x O 2 . The aim of this study was to elucidate the structural effects of Al doping with particular attention to the surface properties of the material. X-ray diffraction data reveal that Al induces monoclinic stacking faults in orthorhombic LiAl x Mn 1-x O 2 and at Al contents of ~5% the preferred cation ordering becomes that of monoclinic LiAl x Mn 1-x O 2 . X-ray photoelectron spectroscopy measurements show that the Al is homogeneously incorporated throughout the grains up to its solubility limit, and no surface enrichment of Al is observed. The XPS data indicate that Mn in the near-surface region of the material is predominantly present in its Y3 oxidation state, even when annealed to temperatures of up to 250 Β°C.