Electric field-enhanced separation of polyethylene glycol (PEG) from an aqueous electrolyte solution of bovine serum albumin has been carried out. Experimental results show significant improvements in both the permeate flux and the PEG transmission with the application of a suitable d.c. electric field. A mass transfer model based on film theory is proposed for prediction of permeate flux and observed retention of PEG. The model uses a single parameter, namely real retention (R-r2) of the PEG which is evaluated by optimizing the experimental values of steady state permeate flux and the permeate concentration. Model predictions are in good agreement with the experimental data.