Use of methanol or ethanol in the magneto-biotechnological technique was found to be enhance citric acid production in a magnetic drum contactor operation with Aspergillus niger AJ 117173. Continuous and repeated-batch fermentations were conducted with the addition of 2% ethanol. Continuous fermentation for 50 d gave a better citric acid yield (85%) and average productivity (3.8 g.l(-1).d(-1))than repeated-batch fermentation over 60 d (65%, 2.3 g.l(-1) d(-1)).