Ketoprofen (KTP) is a widely used anti-inflammatory drug. In this paper the validity of a trained version of the Jouyban-Acree (J & A) model is evaluated to predict the solubility of KTP in ethanol + water cosolvent mixtures. The usefulness of the solubility log-linear equation proposed by Yalkowsky and Roseman (Y & R) is also evaluated for the same drug in this cosolvent system. The solubility estimation is studied as a function of temperature and cosolvent composition. The J & A and Y & R models require only the experimental solubility values in the pure solvents at all the temperatures evaluated. The calculated values by using both models deviate notoriously from experimental values in several cases.