The potential energy hypersurface of the SiOH-HSiO system has been investigated using ab initio electronic structure theory. The geometries and physical properties including dipole moments, harmonic vibrational frequencies, and associated infrared (IR) intensities for the two equilibrium and isomerization (1,2 hydrogen shift) transition state structures have been determined employing self-consistent-held (SCF) and configuration interaction with single and double excitations (CISD) methods. At the CISD optimized geometries, single point energies of the three stationary points were evaluated using coupled cluster with single and double excitations (CCSD) and CCSD with perturbative triple excitations [CCSD(T)] levels of theory. In the correlated procedures three different frozen core schemes (6 frozen core, 2 frozen core, and 0 frozen core) have been applied to examine the importance of Is, 2s, and 2p con electrons. With the SCF method two isomers (A and B) were found for HSiO. However, at the CISD level of theory structure B with the bond angle of about 93 degrees has collapsed to structure A with the bond angle of about 122 degrees, confirming the findings of lower level studies. At the highest level of theory, CCSD(T) with triple zeta plus double polarization (TZ2P) augmented with higher angular momentum and diffuse functions TZ2P(f,d) + diff basis set, TZ2P(f,d) + diff CCSD(T), the energy separation between SiOH and HSiO is predicted to be 12.1 kcal/mol. This energy separation becomes 9.8 kcal/mol with the zero-point vibrational energy (ZPVE) correction. With the same method the classical energy barrier for the exothermic isomerization reaction (HSiO-->SiOH) was determined to be 25.8 kcal/mol and the activation energy (with the ZPVE correction) becomes 24.1 kcal/mol. The two frozen core approximations have generated 0.005 Angstrom (6 frozen core) and 0.001 Angstrom (2 frozen core) in error for the SiO bond length compared to no frozen core method. In energetics these two frozen core schemes have produced errors of +/-0.40 kcal/mol for the CCSD and CCSD(T) methods and error of +/-0.95 kcal/mol for the CISD method.