Background:This research deals with the manufacture of sodium sulphides and sodium sulfhydrate in an isothermal multiphase chemical reactor to produce concentrated aqueous solutions of sodium sulfhydrate (greater than 43%) through Gas-Liquid-Solid reactions from hydrogen sulfide and hydroxide of sodium at 50%. Methods:A method is proposed that integrates the recovery of hydrogen sulfide from an industrial chemical process where the H 2 S gas is generated as a sub product, the strategy of the developed process was integrated into a manufacturing plant of dithiophosphoric acids (ADTF) where it was possible to recover the hydrogen sulfide in the form of an aqueous solution of NaHS with a concentration higher than 43%. Results:The experimental tests showed that the biphasic reaction mixture formed by Na 2 S, NaHS and H 2 O with global compositions of 13.3%; 26.9% and 59.7% respectively, is appropriate to obtain 43% sodium sulfhydrate in a stirred tank reactor, operated at temperatures ranging from 50°C to 55°C, where gaseous hydrogen sulfide is continually bubbled. Conclusion:Sodium sulfide (specifically Na 2 S.5H 2 O crystals) of the biphasic mixture is produced from a solution of sodium sulfhydrate (43% NaHS) and aqueous sodium hydroxide (50% NaOH). The environmental problem generated by the H 2 S was solved with a 90% recovery in the multiphase reactor and 5% in the safety absorber.