Endohedrally hydrogen doped C-60 systems, nH(2)@C-60 (n : 9,12,15,19,21,24) have been theoretically investigated at the level of AMI (RHF) type quantum chemical treatment. It has been found that n : 24 is the maximum number of hydrogen molecules which should result a stable composite system. The calculations indicate that all these structures are stable but highly endothermic. Also some geometrical and physicochemical properties of these structures are reported. (C) 2003 Elsevier B.V. All rights reserved.