A method for the utilization of reaction water formed during the synthesis of hydrocarbons from synthesis gas in a GTL process includes the cleaning of oxygenates while quenching of the synthesis gas at a temperature of more than 500° C. while in contact with a catalyst for steam conversion of oxygenates, and the degasification of the cleaned up reaction water. Cleaned up and degasified water is utilized for cooling synthesis gas to a temperature of lower than 400° C. and for water steam production. The invention ensures efficient treatment of reaction water with removal of oxygenates, the use of obtained treated water as boiler feed water, and for the production of water steam.