Rubberwood sawdust comprises cellulose, serving as a feedstock for bioethanol production. Cellulose from pretreated rubberwood was transformed to reducing sugars by enzymatic hydrolysis via a crude enzyme sourced originate from Aspergillus niger. This research aims to clarify the kinetics of enzymatic hydrolysis for durations of 5, 10, 15, 20, and 25 hours at enzyme-to-substrate ratios of 1:20, 2:20, 3:20, 4:20, 5:20, and 6:20 (v/w). The results showed that, at an enzyme-to-substrate ratio of 6:20 (v/w) for 25 h, the maximum quantity of reducing sugars was approximately 3.15 g L-1. The FPase activity was 255.1672 U mL-1, whereas the CMCase activity reached 235.9105. The Michaelis–Menten kinetic model states that the maximum rate ranges from 6.50×10-7 to 2.6×10-6 Mol L-1 s-1, and the reaction rate produces a Michaelis constant between 0.0051 and 0.0055.