The solubility of N-chlorobenzenesulfonamide sodium and N-chloro-4-toluenesulfonamide sodium in ethanol + propan-2-ol solvent mixtures can be exactly measured by a laser technique at atmosphere pressure ranging from 278.00 K to 323.00 K. Then, using the combined binary solvent CNIBS/Redlich-Kister equation, the results of these measurements were correlated accurately. The experimental solubility and correlation equation in this work are of much value and widely used in the industrial purification process. Moreover, the thermodynamic properties of dissolution process were also calculated with the experimentally determined solubility data. (C) 2013 Elsevier B.V. All rights reserved.