Transport of copper(II) ions through bulk liquid membranes is studied in various experimental conditions. The results obtained are analyzed by using the concepts and methods of chemical kinetics. This approach allowed kinetic equations to be established which are sufficiently general to account for a large variety of transport kinetics (steady or nonsteady state, first or zeroth order, diffusion or reaction controlled, reversible or irreversible), to identify clearly the rate-determining steps, and to propose a detailed mechanism at the molecular level. The important role played by the interfaces is also demonstrated.