Pseudoalloy Mg-Mm-Ni prepared by sintering of a mixture of three hydrides MgH(2), MmH(3), Mg(2)NiH(4) and pseudoalloy-carbon composites obtained via ball milling of the pseudoalloy (90 mass%) with graphite or carbon nanofibers (10 mass%) were investigated by means of the thermal analysis, chemical analysis, Brunauer Emmett Teller analysis, and X-ray diffraction. Data on hydrogen sorption and desorption by the materials showed that the optimal ball milling time for the composites was 90 min, and the addition of carbon nanofibers during the ball milling enhanced the hydrogen sorption rate of the composites as compared to that of the pseudoalloy. The pseudoalloy-carbon composites demonstrated longer cycling durability than the pseudoalloy. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.