An MP2/CBS approach has been proposed to calculate the adiabatic electron affinities (EAs) for the heteroatomic molecule SO4. The method involves the approximation to the complete basis set (CBS) limit at the MP2 level. The zero-point vibrational energy correction, the diagonal Born-Oppenheimer correction, and the scalar relativistic effect correction have been also made in the calculations. The present MP2/CBS predictions are found to be in good accord with the available experimental values. (C) 2008 Elsevier B.V. All rights reserved.