The stabilization of O + O-2 by collision with Ar is calculated using a quantum inelastic scattering approach with full-dimensional bound and unbound O-3 vibrational wavefunctions. Calculations of the stabilization probability are presented for seven combinations of O-16, O-17 and O-18 atoms, at one total energy, zero impact parameter, and three initial orientations of Ar with respect to a body-fixed coordinate system. The importance of van der Waals well bound states and the probable importance of long-lived resonant states for stabilization is shown. Comparison of ratios of calculated stabilization probabilities with experimental rate constant ratios shows encouraging and consistent agreement. (c) 2005 Elsevier B.V. All rights reserved.