The electrochemistry of different minerals gives an important contribution to a better under standing of phenomena in unit processes as precipitation, atmospheric leaching, pressure leaching and flotation, but special knowledge is needed when the potential measurements are used in the process study. Outokumpu has introduced potential measurements for basic research and laboratory-scale process studies as well as for process control of commercial processes. Several types of processes have been examined, starting already in the eighties, In the present paper some examples of the benefits of using electrochemical potential measurements in flotation processes are discussed and some examples of the utilization of electrochemical mixed-potential measurements in practice are shown, The complexity of flotation processes will also be discussed as well as the particular matters to which attention should be paid in process planning.