A new model for the excess Gibbs energy of hydrotrope solutions is presented. This model is based on the local composition model by Chen et al. Hydrotropes are usually organic salts that can increase the solubility of organic and inorganic compounds in water. The proposed model has five adjustable parameters; one of them is related to long-range forces, and four of them are related to short-range forces. Long-range forces are modeled by the Pitzer-Debye-Huckel equation. However, in our model, the effect of the molecular solute on the dielectric constant of water has also been considered. Modeling of short-range forces is based on local composition concepts. The model parameters are obtained using experimental data for six hyrotropes with four solutes at different temperatures. The water solubility of molecular solutes in the presence of hydrotropes has been calculated for different systems. Accurate results are obtained.(c) 2005 American Institute of Chemical Engineers.