The alane-NH3-nXn (n = 0-3; X = F, Cl) donor-acceptor complexes have been investigated at the G2-(MP2) level of theory. The G2(MP2) results show that the successive fluorine and chlorine substitution on the nitrogen decreases the stability of H3AlNH3-nFn and H3AlNH3-nCln complexes although the basicity of the NH3-nFn and NH3-nCln ligands decreases with this substitution. The NBO partitioning scheme shows that the shortening of the N-F and N-Cl bond lengths, upon complexation, is due to an increasing "s" character in these bonds. A linear relationship between the G2(MP2) complexation energy and the G2(MP2) proton affinity of the corresponding Lewis bases has been established and discussed.