Ab initio quantum mechanical methods, including the self-consistent field (SCF), single- and double-excitation configuration interaction (CISD), single- and double-excitation coupled cluster (CCSD), and the single-, double-, and perturbative triple-excitation coupled cluster [CCSD(T)] have been applied to three stationary points on the SiH7+ potential energy hypersurface. Double-zeta plus polarization (DZP) and triple-zeta plus double-polarization [TZ2P and TZ2P(f,d)] basis sets were employed. The C-2 structure, where two symmetry-equivalent Hz subunits complex the SiH3+ cation, was found to be the global minimum, in agreement with the findings of Liu and Zhou (J. Phys. Chem. 1993, 97, 9555). The bound vs free H-2 harmonic vibrational frequency shift obtained at the TZ2P CCSD level (259 cm(-1)) is 36 cm(-1) less than the experimental frequency shift (295 cm(-1)), compared with the shift obtained by Liu and Zhou with second-order perturbation theory, which was 33 cm(-1) higher than the value from experiment. The theoretical rotational constants are compared with the experiments of Okumura’s group. The dissociation energy D-0 of SiH7+ to yield SiH5+ and H-2 is sizable, 4.6 kcal/mol [TZ2P(f,d)] CCSD-(T) + ZPVE(TZ2P CCSD)], much larger than the analogous value for CH7+.