With respect to first-principles calculations, the sandwich-type dinuclear organometallic compounds as (C(5)H(5))(2)TM(2) (M = Sc and Ti) can adsorb up to eight hydrogen molecules. The corresponding gravimetric hydrogen-storage capacity is 6.7 wt% for (C(5)H(5))(2)Ti(2) and 6.8 wt% for (C(5)H(5))(2)Sc(2). The multimetallocenes (e.g., CpTi(3)Cp and CpTi(4)Cp) complexes can further increase the H(2) adsorption capacity to 8.7 wt% and 10.4 wt%, respectively. These sandwich-type organometallocenes proposed in this work are favorable for reversible adsorption and desorption of hydrogen under ambient conditions. These predictions will likely provide a new route for developing novel high-capacity hydrogen-storage materials. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.