Certain factors affecting production of extracellular and cell-bound glucose oxidase by Aspergillus niger were investigated. The intention was to maximize total glucose oxidase activity of academic and potential commercial application by the selection of the appropriate strain and consecutive optimization of growth media and conditions. It wars possible to identify combinations resulting in the utilization of molasses as the best carbon source and enhancing enzyme activity approximately 40-fold. Glucose oxidase activities as high as 5.7 U ml(-1) were produced, comparing favorably with those reported for other enzyme-producing microorganisms. These activity levels were obtained with molasses, indicating an economically attractive process for enzyme production. In addition, our work identified CaCO3 as a particularly strong inducer of glucose oxidase activity.