Abstract: An improved liquid-liquid extraction process for separating metals from each other in which an aqueous solution containing metals is mixed with an organic solution containing an extraction agent that releases hydrogen ions. A mixture of aqueous dispersed phase and an organic continuous phase is formed and the pH of the aqueous dispersed phase is controlled by the addition of a neutralizing agent to the mixture of the aqueous dispersed phase and the organic continuous phase on the basis of pH measurements made with pH electrodes immersed in the mixture of the phases. These direct measurements permit accurate adaptation of the rate of addition of the neutralizing agent to the rate at which hydrogen ions are being released so that the pH of the aqueous dispersed phase is kept substantially constant. The phases are separated from each other after transfer of metal ions from the aqueous to the organic phase, and the separated metal values are recovered.