The selective solvation of silver(I) iodate was studied in methanoldimethyl sulohoxide mixtures at 30° C by solubility and EMF measurements. The solubility of the salt increases continuously with the addition of dimethyl sulphoxide after a slight decrease into XDMSO =0.1. The Gibbs energy of transfer of silver cation (determined on the basis of ferrocene reference method) decreases continuously while that of the iodate ion increases with the addition of dimethyl sulphoxide. The solvent transport number passes through a maximum (Δ = 2.0) around XDMSO = 0.5. These results were interpreted as arising due to a heteroselective solvation of the salt, the silver ions being preferentially solvated by dimethyl sulphoxide and the iodate ion by methanol in these mixtures. © 1981 Indian Academy of Sciences.