The roles of pulp potential, collector and depressants on the flotation of pyrite, chalcopyrite and galena were studied by using two-liquid flotation technique. The potential was adjusted by reducing (Na2S and Na2S2O4) and oxidizing (H2O2) agents. Cyanide and chromate were employed as depressants and potassium amyl xanthate was used as sulphydryl type collector. Pyrite and chalcopyrite showed collectorless flotation. while all three minerals were floatable when reduced with Na2S. Flotation of pyrite and chalcopyrite with and without collector took place in the same potential region whereas galena was floatable with collector to more reducing potentials. Depression with cyanide was potential dependent whereas with chromate it was not. (C) 2007 Elsevier Ltd. All rights reserved.