Structures and energies of the parent hexa-, hepta-, and octacoordinate alonium ions AlH6+, AlH72+, and AlH83+ respectively, were calculated at the ab initio MP2/6-31G** and QCISD(T)/6-311G** levels. The C-2 upsilon symmetrical 4, C-3 upsilon symmetrical 7, and T-d symmetrical 10 were found to be the energy-minimum structures of AlH6+, AlH72+ and AlH83+, respectively. The related structures of AlH4+ (6), AlH52+ (9), and AlH63+ (11) were also calculated at the ab initio MP2/6-31G** level. Formation of AlH6+ by protonation of AlH5 was found to be strongly exothermic by 181.0 kcal/mol. The protonation of AlH3 to AlH4+ (6) is also highly exothermic by 176.4 kcal/mol.