The thermodynamics of partitioning of water between saline aqueous phase and organic phase was studied to determine the feasibility of desalination by directed solvent extraction using octanoic acid as the solvent. The experimental results were fitted to an extended UNIQUAC model and used in process calculations. Extractive desalination was found to have an order of magnitude higher consumption compared to the state-of-the-art in desalination using reverse osmosis. The equivalent electricity consumption in extractive desalination is estimated to be approximately 30 kWh/m(3) of salt-free water as opposed to 3-5 kWh/m(3) for a reverse osmosis process. Capital costs for the heat exchangers alone are 25-fold higher than the total capital expenditure for an equivalent reverse osmosis process. A fundamental thermodynamic obstacle to the performance of extractive desalination was discovered; the contactor, the device used to countercurrently contact the organic phase with the saline aqueous phase in order to extract water into the former, is severely pinched and can yield only three effective theoretical contact stages. This leads to excessively large circulation of solvent and the concomitant losses in pumping and temperature swing. (C) 2014 Elsevier B.V. All rights reserved.