The H5O2+ system has been studied using a variety of coupled cluster methods based on a Brueckner reference determinant with levels of correlation up to double and perturbatively treated connected triple excitations [B-CCD(T)]. Basis sets as large as the triple-zeta plus double polarization basis augmented with f functions on oxygen and d functions on hydrogen [TZ2P(f,d)] were used. Harmonic vibrational frequencies were also predicted. In contrast with previous high-level ab initio studies, a stationary point of C-1 symmetry was not found. An absence of imaginary vibrational frequencies at all levels of theory for the stationary point of C-2 symmetry proves it to be the global minimum, lying only similar to 0.4 kcal/mol lower in energy than the transition state of C-s symmetry.