Process for the purification of an aqueous stream coming from the Fischer-Tropsch reaction which comprises: feeding said aqueous stream containing the organic by products of the reaction to one or more pervaporation units, said one or more pervaporation units comprising at least one polymeric pervaporation membrane, obtaining two outgoing streams: —an aqueous stream (i) enriched in alcohols having from 1 to 8 carbon atoms, preferably from 2 to 4 carbon atoms; —an aqueous stream (ii) enriched in water.