Ultrafiltration of a ternary system lysozyme/sodium chloride/water is modelled through the integration of the surface force-pore flow (SFPF) model with the feed flow transport equations and recurring to computational fluid dynamics (CFD). Permeation experiments are performed using an ultrafiltration laboratory cell with a slit feed channel (h = 1.2 mm << l = 200 mm, w = 30 mm) and a laboratory-made cellulose acetate membrane characterized by an hydraulic permeability of 5.9 x 10(-11) m s(-1) Pa-1 and a molecular weight cut-off of 60 kDa. The operating pressures ranged from 2 to 8 bar and the salt concentrations from 6 x 10(-4) to 0.1 M. The Ultrafiltration performance is simulated at different operating pressures and salt concentrations through multicomponent mass transfer modelling with incorporation of membrane/protein electrostatic interactions. The predictions of the lysozyme apparent rejection coefficients and permeation fluxes are in very good agreement with the experimental results. (c) 2006 Elsevier B.V. All rights reserved.