This study aims to investigate the nature of interactions between pyrite and sodium diisobutyldithiophosphinate (DTPI), a dithiophospinate type collector, with respect to the pulp potential (Eh), and pH. Cyclic voltammetry (CV) technique was employed at certain potential ranges and slightly acidic, neutral and alkaline solutions in order to identify the electrochemical behaviour of pyrite and DTPI individually, as well as the possible mutual reactions occurring among pyrite surface and DTPI. In addition, the change in the hydrophobicity of the pyrite surface was also evaluated in the absence and presence of DTPI as a function of Eh and pH through electrochemical contact angle measurements. These two phases were complemented by DRIFT spectroscopy analysis with polarized and DTPI induced pyrite samples at various potential values so as to determine the origin of species forming on pyrite surface. At the end of the study, all these three distinct methods indicated that the adsorption of DTPI on the pyrite surface relied on chemical mechanisms rather than an electrochemical interaction. (C) 2003 Elsevier B.V. All rights reserved.