Molar conductances of Bu4NBPh4, Bu4NI, Bu4NBr, Pr4NBr, Et4NBr, NaBPh4 and NaI have been measured in the concentration range (0-50) x 10(-4) mol dm-3 in dimethyl-sulphoxide (DMSO)+ dioxane mixtures containing 90, 75, 60 and 45 mol% DMSO at 35 and 45-degrees-C. The entire conductance data have been analysed and the limiting molar conductance values for various electrolytes have been obtained. The limiting ionic conductance (lambda1) have been evaluated to calculate the solvated radii r(i)) and the ionic Walden product (lambda(i)eta0) at 35 and 45-degrees-C. The variation of ionic Walden product and solvated radii has been examined as a function of solvent composition and temperature to throw light on the solvation behaviour of these large tetraalkylammonium ions.