Lignocellulosic biomass is a competitive alternative to replace fossil fuels and to be utilized as feedstock for the sustainable and carbon-neutral generation of fuels, chemicals, and high added-value materials. To realize this potential, a cost-effective and low energy-demanded biomass pretreatment technology is highly required. This thesis is mainly focused on the fractionation of lignocellulosic biomass using a protic ionic liquid following by a chlorine-free bleaching process to obtain dissolving pulp fiber (DPF) at industrial scale. The aim of this work is to achieve process improvements leading to an increase in the product’s quality and to identify the environmental burdens in each step of the process.