Layered transition metal oxides containing more than one transition element are considered for applications in electric vehicles. In these compounds new and improved properties may result from the combination of element specific properties. At the same time the arrangement of species within the transition metal layer is one aspect that may affect the Li intercalation behavior and hence the electrochemical properties. Here we present a microstructural study on a series of Li[Ni-1 (-) Mn-x(x)]O-2 compounds where the oxidations state and arrangement of TM ions are characterized by SQUID magnetometry and single crystal electron diffraction. Our results show that in-plane long range ordering increases with Mn content and that Li/Ni interchange takes place in all powders but seems to be highest in Mn-rich compositions. During chemical delithiation Li is removed from the TM layers leading to a decrease in percentage of long range ordering. (C) 2010 Elsevier B.V. All rights reserved.