Separation of bovine serum albumin from aqueous electrolytic solution has been carried out by electric field assisted cross flow ultrafiltration using polyphenylene ethersulfone membrane of molecular weight cut-off (MWCO) 30 kDa in a rectangular channel. A theoretical model is developed under the turbulent flow regime including the effect suction for osmotic pressure controlled electric field assisted ultrafiltration. Similarity solution technique is applied to solve the governing partial differential equations of the concentration profile in the developing mass transfer boundary layer over the membrane surface. The proposed model is used to predict the permeate flux and membrane surface concentration. Effect of d.c. electric field on the variation of membrane surface concentration and permeate flux along the length of the channel is also quantified using this model. The expression of Sherwood number relation for estimation of mass transfer coefficient is derived. The analysis shows that there is a significant effect of electric field on the mass transfer coefficient. Parametric study has been carried out to observe the effect of feed concentration, electric field, cross flow velocity and pressure on the permeate flux and membrane surface concentration. The value of critical electric field has also been quantified from the knowledge of permeate flux. The predictions from theoretical analysis are successfully compared with the experimental results under a wide range of operating conditions. (C) 2010 Elsevier B.V. All rights reserved.