Research into the application of microwave irradiation in the comminution of ores has made great progress in recent years, creating a demand to understand the effects of this technique on downstream processes, especially flotation. The present work investigated the floatability of untreated and microwave-treated chalcopyrite, pentlandite and pyrrhotite samples using potassium amyl xanthate and sodium oleate as collectors. The effects of the exposure time on each mineral's recovery at different concentrations, pH and particle sizes were studied through microflotation, and the adsorption of the collectors was analyzed by electrophoretic zeta potential measurements. Microwave irradiation led to the decrease in the floatability of chalcopyrite and pyrrhotite in the presence of xanthate, at the pH values investigated, whereas no significant change was observed for pentlandite. The flotation of the microwave-treated minerals required greater sodium oleate concentration. The treated and non-treated pentlandite and pyrrhotite samples did not float at pH 10. Although the treated chalcopyrite and pentlandite displayed low recoveries at all pH values, the treated pyrrhotite displayed high floatability at acidic and neutral pH. The recovery of the microwave-treated sulphide minerals was more affected by the particle size in the tests with potassium amyl xanthate than with sodium oleate. The overall results presented by this work indicate potential conditions to achieve selectivity between the microwave-treated chalcopyrite, pentlandite and pyrrhotite. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.