The experimental was carried out to study the filtration behavior in the filtration of proteins, bovine serum albumin (BSA) and bovine gamma-globulin (BGG) under the influence of electric field strength (E). The protein-membrane interactions play important roles in the filtration behavior during the process. The pH changed gradually during the operation time resulted in the changes in physicochemical properties of membrane and protein solutions. It was found that the lowest permeate flux occurred at the IEP of both BSA (pH 4.9) and BGG (pH 5.86-6.70). The high permeate flux was found to be at higher and lower than IEP of the proteins due to electrostatic interaction/repulsion between protein and membrane surface. (C) 2008 Elsevier B.V. All rights reserved.