The separation factor of Co/Ni and permeation rate of Co across the supported liquid membrane (SLM) containing HEH(EHP) as a carrier have been studied. The mathematical model developed previously for the single permeation of cobalt was extended to the simultaneous permeations of cobalt and nickel. The predictions by the extended model were compared with the experimental data obtained using a batch type permeator of a thin sheet SLM. In addition, the effects of the operation variables on separation performance of a SLM unit were simulated in view of the multi-stage cascade operations.