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.