Numerical simulations were implemented to predict a disc-type single cell performance with gas seal at anode off-gas recycle from the previous experimental results without gas seal. It was clarified that 70% DC electrical efficiency with seal could be expected at 700 degrees C, 387 mA cm(-2) (90% fuel and 45% air utilizations) and recycle ratio r = 0.67 by 17 mV enhancement in the cell voltage with gas sealing. The efficiency would be increased by 1 percentage point compared to one without seal. Distribution of current density, anode gas composition, and electromotive force in the cell with seal was also elucidated. Furthermore, it was revealed that change in current density, H-2 concentration, and electromotive force between the cell inlet and outlet could become smaller as the recycle ratio increases. It was also found that differences in recycle ratio (r = 0.56, 0.67, 0.74) could influence cell voltage only by +/- 1%.