Solubility data were measured for 1-(4-methyl-1-naphthyl) ethanone in an aqueous ethanol solution at a temperature range of 288.20-308.20 K using a laser monitoring system. These data were regressed by lambda h and modified Apelblat models. lambda h and modified Apelblat equations provided an accurate mathematical representation of the experimental results. The root mean square deviations of lambda h models were lower than those of Apelblat models. The results indicated that the lambda h equation most suitably described the solid-liquid equilibrium of 1-(4-methyl-1-naphthyl) ethanone in aqueous ethanol solution. Further, this study provided valuable data for the mechanism and preparation of the available crystal form of 1-(4-methyl-1-naphthyl) ethanone. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.