The ever expanding trend of the palm oil industries in Malaysia brings about environmental concern with various parties calling for global practice of sustainable palm oil production. In as much as researches in processing technologies are ongoing, utilization of palm oil industries residues as a substrate for cellulases production has received little attention. This study addressed on the effect of pressed pericarp fibers sterilization on cellulase production by Pycnoporus sanguineus grown in shake flask culture using a statistical approach. Optimum condition was obtained in 70% (v/v) palm oil mill effluent supplemented with 6 g L-1 sterilized palm pressed fibers at pH 6.77 and 350 rpm with CMCase, FPase and β-glucosidase activities and net changes of biomass and suspended solid at 50.11, 29.01, 5.58 IU mL-1 and 2.49 g L-1, respectively. Under such conditions, the predicted maximum growth and cellulolytic enzyme production were in good agreement with the experimental data with 0.016-0.358% error.