Cokery wastewater was studied for alky., phenols, phosphate P, ammonium, nitrite and nitrate N, cyanides, rhodanides, thiosulfates, sulfates, org. C and pH changes during storage for 48 h optionally under aeration, in presence of activated sludge and after addn. of Na2S2O3, NH4Cl and/or KCN. A decrease in pH was observed because of the biochem. oxidn. of thiosulfates to H2SO4. The activated sludge obtained from the cokery wastewater treatment plant did not show any nitrifying activity.