The solubilities of cloxacillin sodium in binary butyl acetate + methanol and ethyl acetate + methanol solvent mixtures were measured at temperatures ranging from (283.15 to 298.15) K. The experimental data can be well correlated by the CNIBS/Redlich-Kister model. The results show that the solubility of cloxacillin sodium increases with increasing temperature and mole fraction of methanol in these two binary mixed solvents.