To investigate the effects of NaOH and ethanol on the solubility of disodium decanedioate in water, the solubilities of disodium decanedioate in two aqueous solutions (aqueous NaOH solutions and aqueous ethanol solutions) were determined in a temperature range of (284 to 345) K. The solute-free mole fraction of NaOH and ethanol in the solvent mixtures extended from 0 to 0.084 and 0 to 0.472, respectively. With the increase of the mole fractions of ethanol (or NaOH) in solvent mixtures, the solubilities decreased obviously. Alcohol-out and alkali-out phenomena could be evidently observed, between which the alkali-out effect was more prominent. The determined data were correlated with the new electrolyte nonrandom two-liquid (E-NRTL) model, and the root-mean-square deviations of solubility temperature varied from (0.26 to 0.91) K.