A triple-layer site-binding model was used to describe the electrical properties of the iron-treated sphalerite/water interface. The surface ionization constants were determined by fitting zeta potential data to the model using MATLAB software, Using electrokinetic data and knowing surface ionization constants, the species distribution both at the sphalerite surface and in solution as a function of pH was evaluated, The relevance of this species distribution to sphalerite flotation is discussed.