Permeation rates of cobalt ions across a supported liquid membrane containing HEH(EHP) as a carrier have been studied, A mathematical model considering the transfer resistance of the counter ion is developed to analyze the cobalt permeations for the system where the cobalt concentration in a feed phase varies over a wide range. The conditions of a receiving phase are also incorporated in the model to understand the effect of the hydrogen concentration in a receiving phase. Experiments are carried out using a batch type permeator of a thin sheet supported liquid membrane and the results are compared with the model predictions,