Aspergillus niger has been shown to produce extracellular exo-and endo-inulase.  This enzyme was used for inulin hydrolysis to produce syrups with more than 75% D-fructose.  High fructose syrup can be used as low caloric sweetener.  From this important point and others, Aspergillus niger was used in this study for inulase production and the results revealed that: maximal yield of enzyme is attained within 96 hours after inoculation.  Inulin, dalhia tuber, chicory roots and artichoke tuber were found as the best carbon sources for enzyme production and to induce its productivity.  Yeast extract and corn steep liquor stimulated the enzyme secretion.  pH 5.5 and 35^oC were found as the pH and temperature optima for enzyme biosynthesis. A rapid hydrolysis was observed as a result action of inulase on inulin for about 20 min at 55 ^oC, which appeared as the suitable conditions for substrate hydrolysis.  pH 5.5 was found as the optimum pH for enzyme activity.  Aspergillus niger inulase hydrolyzed sucrose, raffinose and inulin.  Thus, this enzyme is not specific substrate degrading enzyme and belong to the group of fructano-hydrolyases.  Mg⁺² and Mn⁺² at 1 mM activated the enzyme, while other ions were found as inhibitors. Aspergillus niger inulase hydrolyzed inulin and Jerusalem artichoke with a higher degree of hydrolysis being 71.6 and 89.2%, respectively with 20 units of enzyme for 5 hours.  Therefore, reducing sugars as fructose were raised and may be consumed as low caloric fructose-syrup sweetener and prevent sucrose-intolerant in diabetics.