For the first time, growing cells of Gordonia alkanivorans RIPI90A were used for biodesulfurization (BDS) of diesel. This process was carried out in an internal airlift bioreactor. BDS parameters (oil/water phase ratio and initial sulfur concentration) were optimized in flasks using response surface methodology. Predicted results were found to be in good agreement with experimental results. Initial sulfur concentration had a remarkable effect on BDS process. Maximum removal of sulfur (21 mg/l) can be achieved at oil/ water phase ratio of 25% (v/v) and initial sulfur concentration of 28 mg/l. Moreover, effect of superficial gas velocity (U-g) and working volume (v) on volumetric gas liquid mass transfer coefficient was studied in an airlift bioreactor for BDS of diesel. The best results were achieved at U-g and v of 2.51/min and 6.61, respectively. Subsequently, BDS of diesel was investigated in an airlift bioreactor under optimized conditions. Sulfur reduction after 30 h was 14 mg/l. (C) 2011 Elsevier Ltd. All rights reserved.