A process of continuous citric acid production from sugarcane molasses by fermentation with immobilized whole cells of A. niger KCU 520 is described. Both calcium alginate beads and polyacrylamide gel (PAG) slab entrapment methods were used for immobilization of cells. The optimum fermentation conditions for citric acid fermentation by immobilized cells were sugars, 10%; pH, 4.0; inoculum size, 20%, and temperature, 32-35°C. With calcium-alginate and PAG-immobilized cells, an overall citric acid production rate of 8.5 g and 12.0 g///day (9.3% and 12% sugar conversion to citric acid per day), respectively was achieved in a single-stage bioreactor. When the PAG-immobilized cells were used in a two-stage bioreactor, approximately 20.0 g citric acid/ l /day (20% sugar conversion to citric acid per day) was produced and the PAG-immobilized cells were continuously used for at least 20 days without any significant loss of productivity.Recently, immobilized biocatalyst technology has rapidly emerged as a novel means to utilize enzymes and whole cells as efficient and heterogeneous catalyst for a multitude of industrial and medical applications (1,4,7,15). Immobilization of living organism is found to be more advantageous than immobilization of enzymes as in situ regeneration of activity is merely by supplementing suitable nutrients (5). In addition, whole metabolic pathway of microbe or part of it required for the production of a particular compound, can be efficiently used over a longer period under immobilized state.A number of organic acids are produced by moulds, and citric acid is one of the most important metabolic products, now produced almost exclusively by fermentation, using selected strains of A. niger (2,18). Although much work has