Deposition of ammonia molecules in fullerene has been investigated theoretically by performing semi-empirical molecular orbital calculation at PM3 level within RHF formalism. C-60 cluster has been doped endohedrally by ammonia molecules. Structural and electronic properties of the systems considered have been studied. It has been found that C60 cluster can store at most six ammonia molecules. The ammoniacal endofullerenes, (NH3)(n)@C-60, have been found stable but endothermic. (C) 2003 Elsevier B.V. All rights reserved.