Introduction of pressurized gasification of black liquor in the pulping industry has the potential to give a significant increase in energy efficiency. However, uncertainties about the reliability and robustness of the technology are preventing large-scale market introduction. One important step toward a greater trust in the process reliability is the development of a better understanding of the sensitivity of the process to parameter variations. A computational fluid dynamics model for pressurized gasification of black liquor in an entrained-flow gasifier is presented and used for investigation of the effects of uncertainties in the specific heat capacity of black liquor, the radiation absorption coefficient, and the volatile devolatilization rate using factorial design methodology. It is found that all main factor effects, but none of the interaction effects, influence the considered responses: char conversion, maximum temperature, and outlet temperature. However, the main effects are found to be relatively small and the uncertainties in the examined model parameters would not invalidate the results from a design optimization with the presented model.