Layered metastable lithium manganese oxides, Li2/3[Ni1/3−x Mn2/3−y M x+y ]O2 (x = y =1/36 for M=Al, Co, and Fe and x =2/36, y =0 for M=Mg) were prepared by the ion exchange of Li for Na in P2-Na2/3[Ni1/3−x Mn2/3−y M x+y ]O2 precursors. The Al and Co doping produced the T#2 structure with the space group Cmca. On the other hand, the Fe and Mg doped samples had the O6 structure with space group R-3m. Electron diffraction revealed the 1:2 type ordering within the Ni1/3−x Mn2/3−y M x+y O2 slab. It was found that the stacking sequence and electrochemical performance of the Li cells containing T#2-Li2/3[Ni1/3Mn2/3]O2 were affected by the doping with small amounts of Al, Co, Fe, and Mg. The discharge capacity of the Al doped sample was around 200mAhg−1 in the voltage range between 2.0 and 4.7V at the current density of 14.4mAg−1 along with a good capacity retention. Moreover, for the Al and Co doped and undoped oxides, the irreversible phase transition of the T#2 into the O2 structure was observed during the initial lithium deintercalation.