The electrochemical hydrogen storage properties of Ni nanoparticle coated SWCNT electrodes were investigated. A surface modification technique enabled different amounts of Ni nanoparticles to be deposited on the SWCNT surface, which was first chemically oxidized by 6 N HNO(3). The characteristic properties of the SWCNT samples coated with 4-12 wt.%Ni nanoparticles were examined using a scanning electron microscope with energy dispersive spectroscopy (SEWEDX); micro-Raman spectroscopy; thermal analysis techniques consisting of both thermogravimetric analysis (TGA) and differential thermal analysis (DTA), and Brunauer-Emmett-Teller (BET) measurements. It was found that all of the SWCNT samples coated with 4-12 wt.%Ni nanoparticles possessed a similar pore-size distribution. According to the electrochemical test results, the highest electrochemical discharge capacity of 1404 mA h g(-1) was obtained for the SWCNT electrode coated with 8 wt.%Ni nanoparticles, which corresponded to 5.27 wt.% hydrogen storage. This enhancement of electrochemical hydrogen storage capacity was ascribed to the fact that the Ni nanoparticles act as a redox site, thus leading to an improved electrochemical hydrogen storage capacity. The results indicated that the SWCNT coated with Ni nanoparticles are a potential material for hydrogen storage. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.