The selective flotation of chalcopyrite (CuFeS2) and molybdenite (MoS2) was studied using surface oxidation treatments (i.e., ozone (O-3) and hydrogen peroxide (H2O2)). The results indicated that the oxidation treatments had different effects on the wettability of chalcopyrite and molybdenite. Single mineral flotation results showed that the H2O2 treatment had higher separation selectivity for molybdenite and chalcopyrite compared with that of the ozone treatment. The contact angle measurement and X-ray photoelectron spectroscopy (XPS) analysis results showed that the chalcopyrite surface became hydrophilic owing to the surface deposition of oxidized iron and copper after the H2O2 treatment. On the other hand, the contact angle of molybdenite slightly increased following the H2O2 treatment at high concentrations. Possible mechanisms of this phenomenon were proposed in this work. Moreover, the separation selectivity of each oxidation method was discussed. Flotation tests using bulk Cu-Mo concentrate showed that H2O2 could deliver a flotation result comparable to conventional Cu-Mo flotation using NaHS. (C) 2016 Elsevier Ltd. All rights reserved.