Specific interfacial properties, which affect protein extraction in AOT and AOT-lecithin reverse micellar systems(RVMS), have been studied by using their percolation processes. Solubilization of proteins or synthetic polymers into RVMS by the injection method and its effect on the percolation processes could be easily evaluated by the measurement of electrical conductivity. The percolation process is found to be a sensitive and convenient measure of micro-interface of RVMS solubilizing various polymers or proteins, which clearly reflects the polymer(protein)-micellar and micellar-micellar interactions. The stability of RVMS or micellar-micellar interaction was dependent on the kinds, concentration and molecular weight of solubilized polymers. The value of β, defined as the variation of percolation threshold with the concentration of solubilized polymers, can be utilized to evaluate the stability of RVMS solubilizing polymers or micellar-micellar interactions. The values of β are affected by the hydrophobicity, molecular weight and absolute value of the net charge of the polymers solubilized into the AOT reverse micelles, which were evaluated by using Aqueous Two-Phase Systems (ATPS).