In this paper, we report the synthesis of Mg(OH)(2) NPs and Mg(OH)(2)-rGO nanocomposites (NCs) by microwave assisted co-precipitation method. The crystal phase, structural morphology and functional groups of the as-synthesized samples were analyzed by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR). Raman spectroscopy was used to study the defects in the samples. Raman spectroscopy and the SEM results validate the growth of Mg(OH)(2) NPs on the rGO nanosheets. The chemical composition of the prepared samples was analyzed by EDAX. Optical properties of the as-synthesized samples were studied by UV-visible spectroscopy and the energy band gap was calculated by Tauc relation which shows a decrease in band gap with an increase in the amount of Graphene Oxide (GO) in the NCs. The dielectric properties were studied as a function of frequency over a range of 50 Hz to 5 MHz at room temperature. The value of dielectric constant decreases with an increase in frequency, this could be due to the existence of a polarization process at the border of the rGO sheets and Mg (OH)(2) NPs. The value of dielectric loss shows a decreasing trend with an increase in frequency whereas the larger value of AC conductivity in Mg(OH)(2)-rGO NCs as compared to Mg(OH)(2) NPs approves the restoration of sp(2) network in the graphene sheets. (C) 2017 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.