Contact angle measurements, ultraviolet (UV) spectroscopy and voltammetry were used in this investigation to study the effect of various externally applied potentials on the stability of dixanthogen at synthetic and natural chalcopyrite surfaces. The results of contact angle measurements indicate that synthetic and natural chalcopyrites have similar wettabilities. Their hydrophobic potential range in a 7 x 10(-4) M PAX solution was + 0.04 V to + 0.44 V vs. NHE at pH 10 and was - 0.01 V to + 0.54 V at pH 7. UV spectroscopic results show that dixanthogen began to form on the chalcopyrite surface at a potential of + 0.04 V vs. NHE at pH 10 and - 0.01 V vs. NEE at pH 7. The amount of dixanthogen formed on the chalcopyrite surface initially increased with the increase of the applied potential and then decreased with the increasing potential. The optimum potential range for dixanthogen formation on the chalcopyrite surface was from + 0.14 V to + 0.34 V vs. NHE at pH 10 and from + 0.14 V to + 0.44 V vs. NHE at pH 7. It was difficult to completely remove the dixanthogen film on the chalcopyrite surface. (c) 2005 Elsevier B.V. All rights reserved.