Abstract In this study we present the application of ceramic membranes on the osmotic evaporation (OE) process. Hydrophobic tubular macroporous alumina membranes with 0.2 and 0.8×10 −6 m of mean pore size, have been obtained by grafting inorganic supports with siloxane compounds. These hydrophobic membranes have been provided by Pall Corporation, Exekia Division. The OE process is based on the transfer of solvent from one aqueous solution to be concentrated to a second one (concentrated brine). Both solutions are separated by the macroporous hydrophobic membrane. The transfer is realized in vapour phase through the membrane porosity as a consequence of the difference on water activity between both solutions. The results obtained show that interesting water vapour fluxes could be obtained through these membranes. In addition, the mass transfer observed is directly related with the transmembrane pressure and the operating temperature. Good agreement has been obtained between the experimental results and the values provided by a series resistance model.