The potential energy curves and the spin-orbit couplings for all the electronic states correlating with the lowest dissociation asymptote of S2O have been calculated by accurate ab initio approaches, including full-valence complete active space self-consistent field and internally contracted multi-reference configuration interaction. One-dimensional cuts of the three-dimensional potential energy surfaces are presented for linear and bent geometries, providing useful energetic information on the different paths of formation of S2O, starting from various fragments. (C) 2010 Elsevier B. V. All rights reserved.