We have used two novel "model chemistry" composite computational techniques, CPd-G2thaw and c-SLW3, to determine a sodium cation affinity (SCA) scale comprising 38 small ligands. The CPd-G2thaw and c-SLW3 methods have been developed to yield accurate thermochemical parameters for sodium-containing compounds by redressing shortcomings of existing computational techniques for such compounds. The SCA scale established here shows excellent internal consistency between CPd-G2thaw and c-SLW3 values. These theoretical SCA values are consistently higher (by an increment of 2.8 +/- 1.3 kJ mol(-1)) than the set of precise high-pressure mass spectrometry and Fourier transform ion cyclotron values recently reported and generally also exceed the recent threshold collision-induced dissociation values. Our values are typically 2 to 3 kJ mol(-1) lower than those of a small set of previously reported theoretical "benchmark" values.