The enzymatic saccharification of cassava flour starch with Aspergillus niger glucoamylase was studied in a hollow-fiber enzymatic membrane reactor (HF-EMR). The optimization of the process was also investigated. The substrate was previously gelatinized by extrusion that produced a substrate with a degree of gelatinization and physical properties suitable for the enzymatic process. Typically, continuous saccharification of cassava flour starch in the HF-EMR produced a highly pure product in permeate (i.e., 99.6% glucose) with a global starch to glucose conversion of 97.3%. Results from a factorial experimental design revealed that retention time, enzyme to substrate ratio, and substrate concentration were the variables that most affected the process for starch to glucose conversion and for solid accumulation rate. Empirical models that describe this process were experimentally determined and compared with a theoretical model based on a balance of materials and enzyme kinetics. They wee shown to adequately predict the performance of the HF-EMR.