Arsenopyrite floatability was correlated with the galvanic current, calculated from polarization curves measured during grinding, as well as the amount of oxidized iron, measured by EDTA extraction, in the mill discharge. The adverse influence of galvanic interaction during grinding on arsenopyrite floatability was quantified. The effect of grinding conditions on arsenopyrite surface properties was characterized by X-ray Photoelectron Spectroscopy (XPS) analysis. The more electrochemically active the grinding media, the greater the galvanic interaction between arsenopyrite and grinding media and higher amounts of hydrophilic oxidized iron and oxygen species at the surface. These hydrophilic species impaired the floatability of fine arsenopyrite particles, whilst copper (II) ions improved the floatability of fine arsenopyrite. (c) 2005 Elsevier B.V. All rights reserved.