Ab initio quantum mechanical methods have been applied to an investigation of the oxywater (H2OO)hydrogen peroxide (HOOH) isomerization at high levels of theory. The investigation employed basis sets up to triple-zeta plus double polarization plus f functions (TZ2P+f) and levels of correlation up to coupled cluster including single, double, and perturbatively treated connected triple excitations [CCSD(T)]. Harmonic vibrational frequencies are obtained via finite differences of analytic gradients. Their infrared intensities are also reported. The classical barrier for isomerization of oxywater is substantial (5.7 kcal/mol) at the highest level of theory. Correction for zero-point vibrational energies yields a predicted activation energy of 3.3 kcal/mol. The equilibrium dipole moment of oxywater is predicted to be substantial, namely 4.5 D. Thus, oxywater indeed awaits synthesis.