The solubilities of sodium 4-nitrobenzenesulfonate in binary sodium chloride + water, sodium sulfate + water, and ethanol + water solvent mixtures were measured with temperatures ranging from (273.15 to 323.15) K by a steady-state method. Results of these measurements were correlated by a modified Apelblat equation. Sodium chloride + water was found to be the best solvent mixture for purifying sodium 4-nitrobenzenesulfonate.