Although, within plant cells, the cellulose chains are organized in variable and complex ways, relatively little attention has been paid to the relationship between this “fine-structure” of cellulose and its biodegradation. This work focuses on the influence of the substrata and enzyme concentrations on the enzymatic hydrolysis of microcrystalline cellulose. To determine the effect of the supramolecular structure on the enzymatic degradation of cellulose, three crystalline forms of cellulose: I, II and III, have been examined by systematic analysis of the behavior of these allomorphs during enzymatic hydrolysis; also, the kinetics of biodegradation by the enzyme from Trichoderma reesei was investigated. The kinetic parameters Km and Vmax were evaluated with the integral form of the Michaelis-Menten equation. The initial maximum rate can be considered as a measure of substratum reactivity.