A mathematical model for the mass transfer in a parallel plate countercurrent dialysis system coupled with ultrafiltration operation was developed theoretically and experimentally in this study. The analytical solution was obtained using the Frobenius series method. The influences of retentate and dialysate phase flow rates, ultrafiltration flux and solute sieving factor on the outlet concentrations and mass transfer rate were also represented graphically in this study. The analytical predictions show that the introduction of ultrafiltration effects in a dialysis system leads to considerable enhancement of the separation efficiency as compared to that in a pure dialysis system without ultrafiltration. An experimental apparatus was also set up to confirm the accuracy of the proposed mathematical model, and the comparisons show that a qualitative agreement between the theoretical predictions and experimental results was achieved.