The present invention relates to a process for the purification of an aqueous stream coming from the Fischer-Tropsch reaction which comprises: feeding the aqueous stream containing organic by products of the reaction to a fractionating distillation column or to a stripping column; —condensation of the vaporized stream leaving the head of the column and the removal of a distillate enriched in the heaviest by-products; —feeding the partially purified aqueous stream leaving the bottom of the distillation column, at the head to one or more sensible contact exchangers; —sending a process gas in countercurrent to the tail of the exchanger at a temperature lower than that of the aqueous stream; —sending the process gas enriched in water and part of the residual organic product leaving the head of the exchanger to the Fischer-Tropsch synthesis plant of hydrocarbons; —sending the purified colder water leaving the exchanger directly to further treatment.