This study was aimed to investigate the optimum incubation temperature for cellulases production by Aspergillus niger AUMC 8485, Aspergillus flavus AUMC 8534 and Emericella nidulans AUMC 8581. The obtained results showed that, the optimum incubation temperature for cellulases production as measured by cup-plate clearing zone technique was 35⁵ C for all the studied species. The diameter of clearing zone was 22.0, 24.5, 26.0 mm for Aspergillus niger, Aspergillus flavus and Emericella nidulans, respectively. In case of  exo –D-1,4 gluconase (FP-ase) production, the highest enzymatic activity was obtained at 35⁵ C by all the studied fungal species. Meanwhile, the highest specific activity was recorded at 40⁵ C for A. niger and at 35⁵ C for A. flavus and E. nidulans. At the same time, the optimum incubation temperature for endo- ß- D-1,4 gluconase (CMC-ase) production was recorded at 40⁵ C for A. niger and E. nidulans, and at 35 ⁵ C for A. flavus. The highest CMC-ase specific activity was observed at 40⁵ C for all the studied strains. The maximum amount of reducing sugars found in the culture filtrate at 35⁵ C for A. niger, and at 40⁵ C for A. flavus and E. nidulans. Also, the highest amount of soluble protein was recorded at 35⁵ C for A. niger and at 30⁵ C for A. flavus and E. nidulans