Quantum chemical calculations are performed on the complex formed by silicane and ammonium in order to investigate the binding characteristics and nature of the dihydrogen bond. The calculation results using B3LYP and MP2 methods with the basis sets from 6-31G* to 6-31++G(2df,2pd) reveal that the dihydrogen-bond angle is similar to 180.0 degrees and that the bond length is similar to1.60 Angstrom. The calculated enthalpies of formation of this complex using B3LYP/6-311++G(2df,2pd) and MP2/6-311++G(d,p) methods, corrected by basis-set superposition error (BSSE) and thermal energy, are -5.595 and -4.465 kcal/mol, respectively. Taking into account our CCSD(T)/6-311++G(2df,2p) and G2 results, we suggest that the binding strength between SiH4 and NH4+ is similar to5.0 +/-0.5 kcal/mol. The BSSE released from the B3LYP method seems to converge at the basis set 6-311++G(d,p). In addition, charge distribution, electrostatic interaction energy, and the molecular-orbital coefficient analysis on all molecular orbitals of this complex show that s-s orbital interaction plays a key role in their bindings. Three intrinsic vibrational bands of this complex are identified by the normal-mode analysis on the calculated vibration spectra. The thermodynamic parameters of the possible reaction between SiH4 and NH4+ are also calculated, which show that the equilibrium constants of this reaction are about 4.34 x 10(6) and 1.78 x 10(7) for the B3LYP/6-311++G(2df,2pd) and MP2/6-311++G(d,p) methods, respectively. All of these results are helpful for us to better understand the nature and the characteristics of the dihydrogen bond and exploit its application.