A bucky onion-like composite system of C-20 in C-60 Structure was subjected to semiempirical quantum chemical treatment at the level of AMI-REF type calculations. The composite system was found to be a highly endothermic but stable structure. Strong 'through-space' type interaction between C-20 and C-60 shells should exist resulting a dipole moment originating from C-60 shell to C-20 shell. Thus, the composite system should have anisotropic polarizability. (C) 2001 Elsevier Science BN. All rights reserved.