A high accessibility is an essential prerequisite for a homogeneous substitution of cellulose material. In this study, chemical and enzymatic pretreatments to increase the accessibility of cellulose materials have been investigated. Dissolving pulp has been treated with a monocomponent endoglucanase. Fock's method, a microscale process similar to the viscose process, showed an increase in cellulose yield. Simultaneously, the viscosity decreased. To clarify whether the increase in reactivity was due solely to the decrease in the degree of polymerization, the dissolving pulp was also subjected to acid hydrolysis. At a given viscosity level, the enzymatic pretreated pulp had a higher reactivity than the pulp subjected to acid hydrolysis. To achieve 100% reactivity, according to Fock, the acid-treated pulp showed a lower molecular weight compared to the enzymatic-treated pulp. A monocomponent endoglucanase can thus be used to increase the reactivity and accessibility of dissolving pulp in the viscose process.