The electrochemical oxidation of galena in collectorless and collector flotation systems, particularly in strong alkaline media, were studied. The results show that, as pH values high than 12.5 and potentials below 0.17V, the oxidation products of galena are elemental sulfur and HPbO2-. Elemental sulfur was present on the mineral surface in excess of oxidized lead species due to dissolution of HPbO2-, which is beneficial to the flotation of galena. Under the same conditions, sphalerite and pyrite were depressed as a result of significant surface oxidation. Diethyldithiocarbamate (DDTC) was found to be the most suitable collector for galena flotation in strongly alkaline media. The very potential producing hydrophobic PbD2-the surface reaction product of DDTC with galena, is 0 to 0.2V. Meantime DDTC can depress the surface over-oxidation of galena. Investigations also indicate that, in the range of-0.9V to 0.6V, hydrophobic PbD2 can be firmly adsorbed on galena.