The production of cellulase by the yellowish orange sclerotia producing species, Aspergillus melleus UPAR01 on lignocellulosic material by solid state fermentation (SSF) was investigated. The first experiment was conducted to find out the colony radial growth rate (Kr) of fungus on solid medium using potato dextrose agar (PDA) and incubated at 30°C in the dark. The result shows that the average Kr value of A. mellues strain approximately was 0.77±0.03 cm/day. When the fungus was used to produce cellulase using maize crop residues as the sole carbon source by SSF at 30°C for seven day, the values of FPase, endoglucanase, -glucosidase, and xylanase were achieved at 0.284±0.04, 9.45±0.33, 1.20±0.12, 12.58±0.08 U/mg protein, respectively. The optimal pH and temperature (°C) for the enzymatic activities was expressed by response surface methodology (RSM). The data shows that the optimum pH range was between 5.5 and 5.8 and the optimum temperature ranged from 53 to 59°C. In addition, none of the metal ions and ethylene-diaminetetra-acetic acid (EDTA) induced cellulase and xylanase activities.