The knowledge of hydrocarbon/water phase equilibria is important in the design and operation of equipment for petroleum transport and refining and petrochemical plants. The presence of water in a hydrocarbon mixture can affect the product quality and damage the operation equipment due to corrosion and formation of gas hydrates. Tracing the concentration of hydrocarbons in aqueous media is also important for technical purposes like preventing oil spills and for ecological concerns such as predicting the fate of these organic pollutants in the environment. In spite of its huge interest there was no model able for a qualitative description of the mutual solubility of water and hydrocarbons for a broad range of systems in a wide range of thermodynamic conditions. In this work it is shown that an equation of state incorporating association known as the CPA EoS is able to produce an excellent description of the mutual solubilities of water and several aliphatic and aromatic hydrocarbons in a broad range of pressures and temperatures. (c) 2007 Elsevier B.V. All rights reserved.