Two core-shell materials were made in a continuously stirred tank reactor, one with a Ni(OH)(2) core and a Ni1/2Mn1/2(OH)(2) shell and the other with a Ni1/2Mn1/2(OH)(2) core and a Ni0.17Mn0.83(OH)(2) shell. X-ray diffraction measurements (Cu K-alpha radiation) of the core-shell materials were compared to reference materials which were physical mixtures with the same overall composition. The smaller core peaks in the XRD patterns of the core-shell materials were attributed to absorption of X-rays due primarily to the high manganese contents of the shells. Calculations were performed assuming spherical particles of radius matching results from SEM/EDS measurements. For a 5.5 mu m radius particle with a Ni(OH)(2) core, the shell thickness was calculated from XRD patterns to be 0.47 +/- 0.03 mu m. For a 7.9 mu m particle of the material with the Ni1/2Mn1/2(OH)(2) core, the shell was determined to be 1.77 +/- 0.15 mu m thick. Both these results were found to agree well with the overall composition of the samples as determined by elemental analysis and with spatial EDS measurements. This X-ray absorption modeling technique provides an experimentally simple way to measure the thickness of micron scale shell coatings while sampling all particles, unlike methods such as EDS. (C) The Author(s) 2014. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: [email protected]. All rights reserved.