Theoretical prediction of the formation of hydrogen-rich complexes of s-block metal ions and dihydrogen molecules, MH16, (M = Li1+, Na1+, K1+, Be2+' Ca2+, and Mg2+) is reported. The number of hydrogen molecules attached to the metal cation is the highest ever reported in the literature. The interaction between s-block metal ions and hydrogen is found to be weak and the binding energy calculated by MP2 method using cc-pVDZ basis set is observed to be of the order of -30 to -13.5 kcal/mol and -180 to -60 kcal/ mol for alkali and alkaline earth metal cations, respectively. Using this simple ion-molecule interaction, the possibility of the application of these complexes for developing hydrogen storage materials is discussed. (C) 2007 Elsevier B.V. All rights reserved.