This paper contains the results of Hallimond tube flotation tests conducted with pyrite arsenopyrite and quartz using a cationic type collector called hexyl thioethylamine, as well as the results of electrophoretic mobility (E.M.) tests for the same minerals measured under various conditions. The purpose of this study is to investigate the effect of surface charge of sulphide minerals on the attachment mechanism of a cationic collector. In this regard, the influence of pH and collector concentration on the electrophoretic mobilities of pyrite, arsenopyrite and quartz were monitored. The mobility measurements at various pH values were made in the absence and presence of collector, and the effect of collector concentration on the electrophoretic mobility was determined at constant pH. The results were evaluated in terms of flotation?, electrophoretic mobility, adsorption and IR data The experimental results indicate that flotation of pyrite induced by hexyl thioethylamine is not dependent on the surface charge of the particle. (C) 2000 Elsevier Science Ltd. All rights reserved.