This study shows that between brucite (Mg(OH)(2)) and beta-Co(OH)(2), all the compositions are possible. The solid solution Mg1-xCox(OH)(2) has been synthesized by an easy and fast coprecipitation route and characterized by XRD and TEM. Single phase powders have been obtained. The particles exhibit platelets morphology with a size close to one hundred nanometers. XRD analysis shows an evolution of the cell parameters when x increases and demonstrates that no ordering of the cations occurs. However, extra reflections on TEM electron diffraction patterns seem to indicate that local ordering can exist. The compounds issued from this solid solution could be good candidates as precursors in order to obtain Mg-Co mixed oxide with all possible cationic ratios. (C) 2012 Elsevier Ltd. All rights reserved.