The aim of this study was to determine the influence of photo-irradiation and pH on the mobilization of metals from a complex sulfide ore concentrate containing known semiconductors (PbS, ZnS, CdS, FeS₂, and CuFeS₂). The mobilization of Zn, Fe, and Cd increased under illumination, which is attributed to the semiconductor nature of ZnS, FeS₂, and CdS, respectively. An increase in mobilization of Zn, Fe, and Cd under light is observed with decreasing pH, because of increased surface protonation and the greater oxidizing property of photoholes. The semiconductor nature of PbS and CuFeS₂ is observed at pH 2. However, at higher pH the concentrations of mobilized Pb and Cu are greater in darkness than under illumination. This is attributed to the light enhanced exchange reactions involving dissolved Pb and Cu with metal sulfides more soluble than PbS and CuS.