The effects of uncertainty in mass flux and initial temperature on the predictions of NO and OH from a detailed chemical kinetics model are determined. The Sandia steady laminar one-dimensional premixed flame code is used to solve the chemical kinetics model for a series of flames from 1 to 9.16 atm. The model allows the determination of the variation in the predictions of NO and OH concentrations from small changes in mass flow rate and in the initial gas temperature. The mass flow rate and initial gas temperature are two quantities for which experimental uncertainty exists, but the effect of which is not often considered in chemical kinetics modeling. The results indicate that uncertainty in the mass flow rate can significantly affect the quantitative predictions of NO and OH, while the initial gas temperature has little effect on the flame modeling results.