Three different methods has been used for the hydrolysis of the cotton stalks to reducing sugar and valuable products. These methods involves: (1) Biological degradation by cultivation of Aspergillus niger on cotton stalks in simple media. The bio-products of A. niger growth in cultures filtrate were evaluated after 6 days of incubation with shaking (~120 rmp) at 30⁰C. (2) Dual-step acid hydrolysis (H₂SO₄ 72%, 4%, v/v) at different time and temperature of hydrolysis.(3)- Enzymatic hydrolysis (two sources of cellulases, separately) for 3 days at 37⁰C and pH 4.6. In biological degradation, the highest bioproducts in culture filtrate (1.72 mg/ml reducing sugar; 5.01 and 1.27 U/ml of µ - amylase and amyloglucosidase; 5.92 and 9.31 mg sugar / ml / h of C_x and X enzymes and 2.78 and 2.37 mg sugar / ml / 24h of C₁ and Av enzymes, respectively) were obtained in medium was contained: 10 g cotton stalks, 10g CaCO₃ and 100 ml water. In dual step acid hydrolysis, the high yield of reducing sugar (80.0 %) was obtained with 85 min - first step acid hydrolysis and 60 min second step acid hydrolysis. While, high yield of reducing sugar in enzymatic hydrolysis (14.97 mg / ml) was occurred with solid cellulase.