In this study, the response of the surface of pyrite to copper activation under electrochemically controlled conditions was investigated in the presence and absence of sodium diisobutyl dithiophosphinate (DTPI). The mechanism of interactions between the concerned reagents and pyrite was investigated using cyclic voltarnmetry in solutions of different pH. In addition, contact angle measurements were performed to determine the wetting behavior of the pyrite surface as a function of pulp potential and pH. The results of both the cyclic voltammetry and contact angle measurements were evaluated to identify the nature of the species formed at the pyrite surface and to explain the underlying mechanism. Both phases of the experiments confirmed that the mechanism of copper activation of pyrite occurred through certain electrochemical reactions, whereas the mutual interactions between DTPI-pyrite and Cu-DTPI couples relied on chemical means. (C) 2004 Elsevier Ltd. All rights reserved.