The solubilities of (sodium and copper(II)) sulfate + ethanol + water mixtures have been determined at (278.15, 288.15, and 298.15) K and for the potassium sulfate + ethanol + water system at the same temperatures and also at (308.15 and 318.15) K. The equilibrium composition for different points has been calculated by means of refraction index and density measurements. An empirical correlation for the solubilities of the ternary mixtures has been used to correlate experimental values as a function of the solvent composition. Data fitting shows a good agreement with experimental values.