Nickel hydroxide was deposited via cathodic electrodeposition from low-temperature 0.005 M NiCl(2) bath without using any surfactant or template. The cathodic current density was 1 mA cm(-2) and stainless steel was used as the cathode. The XRD pattern confirmed that the prepared sample has a pure brucite crystal phase of beta-Ni(OH)(2) and the broadening of diffraction peaks showed that the particles size of the prepared beta-Ni(OH)(2) is extremely small. Thermal behavior and composition of the prepared beta-Ni(OH)(2) were investigated by DSC-TG and FT-IR analyses. Morphological characterization by SEM and TEM revealed that beta-Ni(OH)(2) is composed of well dispersed ultrafine particles with size of about 5 nm. The electrochemical properties of the prepared nanoparticles were studied by means of cyclic voltammetry (CV) and galvanostatic charge-discharge tests in 1 M KOH. The prepared beta-Ni(OH)(2) nanoparticles showed excellent capacitance behavior of 740 F g(-1) in the potential window of 0-0.55 V vs. Ag/AgCl. These results make the beta-Ni(OH)(2) nanoparticles as a promising candidate for the supercapacitor electrodes. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.