In this study, the growth kinetics of sulfur oxidizing bacteria, Acidithiobacillus thiooxidans, and the effect of dissolved oxygen were determined in low pH conditions for the effective removal of high concentrations of hydrogen sulfide. A dual growth kinetic was applied to identify the microbial growth rate at different hydrogen sulfide and oxygen concentrations in the liquid. A modified Monod-Gompertz equation was deemed most appropriate to examine the growth kinetic parameters of A. thiooxidans. The half saturation constants of hydrogen sulfide and oxygen for the modified Monod-Gompertz equation were found to be 0.9 and 1.1 mg/L, respectively. In addition, a bioreactor model, where the Monod-Gompertz equation was modified, was applied to simulate dissolved oxygen concentrations required for the removal of hydrogen sulfide. As a result, the dissolved oxygen concentrations were 0.5, 1.0, 1.5, and 3.3 mg/L, which were necessary to remove hydrogen sulfide to less than 10 ppm at the influent concentrations of 100, 500, 1000 and 3000 ppm, respectively. The required minimum dissolved oxygen concentrations under various conditions including reactor volume, gas retention time, and microbial concentrations can be determined using the numerical model developed in this study. Keywords : Hydrogen sulfide, Dissolved oxygen, Bioreactor, Sulfur oxidizing bacteria, Growth kinetics, Numerical model