The equilibrium and kinetics of the extraction of copper with 3-alkylpentane-2, 4-dione (-H, -C2H5, -Ph, and -C8H17) were studied. It was found that the overall equilibrium constant is related to the proton disscoiation constant and that the ratio of the stability constants of the copper chelate, β2/β12was independent of the alkyl chain length of the β-diketone. The rate constants for the reactions between cupric ion and the β-diketones in the aqueous phase were obtained by the relaxation method. The values decreased in the order -H>-Ph>-C2H5. The observed extraction rates were explained by a kinetic model using the measured physicochemical properties.