The extraction-stripping reaction of Cu (II) by LIX 864 in Escaid 100 from aqueous sulphate medium has been investigated. The effects of different variables which should affected extraction-stripping were investigated: kinetics, aqueous pH, strip solution concentration, etc. Numerical treatment of the data suggested the presence of the CuR2 (K-ext= 1.99) species in the organic phase. Equilibrium studies were used to assess the conditions of copper recovery in a continuous counter-current plant using a real leach solution.