Continuous and batch production of citric acid from sucrose has been investigated using Aspergillus niger NCIM 588. Mycelia of A. niger grown on cellulose microfibril forms a uniform and thin mycelial proliferation under controlled conditions of cultivation rich in oxygen. In the fed batch mode using a recycle reactor, the DO of the system was maintained at 20 mg l(-1) using oxygen enriched air. This improved volumetric productivity to 1.85 g l(-1) h(-1) of citric acid, representing an increase of at least 15-fold over results obtained simultaneously using shake-flasks and 1.6-fold over a conventional aerated batch reactor. It was possible to substitute sucrose with sugarcane juice as a carbon source in a fed batch recycle system. An overall specific production rate of citric acid of 0.147 and 0.208 g g(-1) h(-1) was achieved using cane juice and sucrose, respectively. In continuous fermentation, a medium containing 50 g l(-1) of sucrose was allowed to drip through the fabric support at a residence time of 20 h. As a result of interface interaction, a citric acid volumetric productivity of 2.08 g l(-1) h(-1) was achieved for 26 days without any significant loss of productivity.