The process of liquid-phase oxidation of sulfide-containing wastewater by oxygen over porous graphite material "Sibunite" used as a catalyst and adsorbent has been studied. The purification process consists of two consecutive stages. The use of "Sibunite" as a catalyst in oxidation reactions and adsorbent for extraction of organic substances from wastewater allows to carry out oxidation of sulfide ions to sulfates at T=110-130°C (stage 1) and oxidation of organosulfur and organic components at T=200-240°C (stage 2) and completely solve the problem of neutralization of toxic substances contained in alkaline hydrogen sulfide wastewater.