A 0.3% Au/Al2O3 catalyst prepared by the incipient wetness (IW) method was investigated in the continuous-flow liquid-phase glucose oxidation. Therefore, a continuous stirred tank reactor (CSTR) system equipped with an ultrasonic separator was used. The continuous-flow glucose oxidation was carried out at 40 degrees C, pH 9 and 1 bar oxygen partial pressure. Residence time and glucose concentration were varied. The IW gold catalyst showed very high activity and selectivity to gluconic acid within its 710 days of operation and, thus, an excellent long-term stability. Even after severe microbial contaminations of the catalyst, its activity could be completely restored by in situ regeneration with 2-propanol. (C) 2007 Elsevier B.V. All rights reserved.