Aspergillus niger has been tested in a discontinuous process for the pretreatment of fresh green Table Olive Processing Waste waters (TOPW). The influence of seven factors like incubation time, initial pH, dilution, glucose, agitation, (NH 4 ) 2 SO 4 and inoculum size on decolorization was screened by employing a fractional factorial design 2 7-4 . Through factorial plots and analysis of variance, it was found that only glucose and agitation affected the decolorization. Further studies were carried out to adjust the level of determinant factors. Results showed that color removal (62%) was optimum at 150 rpm and 3 g/l glucose. HPLC and FTIR analysis of the treated TOPW suggested that the decolorization occurs through biosorption and biodegradation. Tannase and lignin peroxidase were detected in the cultures. However, only tannase is responsible for the color removal of the TOPW because lignin peroxidase is produced at a low level. Data are reported as mean ± standard deviation of results carried out in triplicate Characteristics