Filtration of sucrose from a mixture of sucrose and poly(vinyl alcohol) (PVA) was studied in a stirred ultrafiltration cell. PVA formed a gel layer and was completely rejected by the membrane. live membranes of different molecular weight cut-off, namely, 1K and 10K were chosen. By the former, sucrose was partially retained and by the latter, it was completely permeable in the absence of PVA. A mathematical model was formulated for simultaneous prediction of permeate flux and observed rejection of sucrose. The characteristics of the gel layer and other relevant parameters of the model were determined by independent sets of experiments. It was observed that the steady-state flux was independent of pressure and equal to the flux of the gel-forming component alone (in the absence of permeating solute). Profiles of permeate flux and observed rejection of sucrose with time agreed well with the experimental observations.