Steady-state and non-steady-state kinetics of coupled transport of copper(II) through liquid membranes made up of technical solvents (escaid 110, kerosene, cosmetic kerosene) and their mixtures with paraffins (n-octane, n-dodecane) have been examined. The influence of the membrane composition on the kinetic parameters (k1, k2, J(a), R(a)) have been also investigated. The present study shows the importance of the nature of the membrane material in establishing transport efficiency. It appears that n-octane is a much more efficient membrane material than technical solvents generally recommended for extraction processes. Striking variations of the kinetic parameters with the membrane composition were observed. However, only a slight improvement in transport efficiency could be obtained by using multicomponent membranes.