We prepared Li(Mn1/3Ni1/3Co1/3-xAlx)O-2 by a solution method, and then investigated the electrode characteristics and average and local structures. From the charge-discharge cycle tests, it was found that Li(Mn1/3Ni1/3Co2/9Al1/9)O-2 exhibited a worse cycle performance than Li(Mn1/3Ni1/3Co1/3)O-2. In order to clarify the reason for this decrease from the viewpoint of the crystal structure, the average structures of the samples were studied by the Rietveld and Maximum Entropy Method (MEM) techniques using the neutron and synchrotron X-ray diffraction patterns. As a result, it was found that the Al substitution did not have a significant effect on the average structure. In order to reveal the local structures, we also performed X-ray absorption fine structure (XAFS) and Pair Distribution Function (PDF) analysis using neutron scattering data. These analyses implied that the stacking of the transition-metal layers varied by the partial substitution of Al for Co, and the arrangement had an influence on the cathode properties. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.007206jes] All rights reserved.