This article presents the results of research intended to obtain a complex alumina-iron reagent based on natural diatomite and industrial products of alumina production for wastewater purification from hydrogen sulfide. The material composition of the obtained samples using X-ray diffraction analysis has been determined. The results of interaction research in the system NaFeO2 – H2S – H2O at 25 оС are given. The results of research on wastewater purification from hydrogen sulfide in Almaty city with the use of ferric sulfate, ferric chloride, sodium ferrite and a complex reagent containing iron at the content of 5.1 mg/l H2S in the initial sample of wastewater are presented.