The IonoSolv process has emerged as a promising wood pretreatment technology in biorefineries, using low-cost, thermally stable protic ionic liquids (PILs) to selectively dissolve lignin and hemicelluloses, leaving a cellulose-rich pulp for enhanced processing efficiency. This method has been successful for various biomass feedstocks, including softwood. Mass transport phenomena play a crucial role in determining delignification rates and overall process efficiency. Previous studies indicate that ILs penetration into wood might be the rate-limiting step in IonoSolv pretreatment. Given the differential solubility of PILs for wood components, their diffusion pathways and mechanisms may differ from traditional fractionation methods. Thus, understanding the distribution and localization of PILs within wood fibers is essential. This research aims to develop methodologies to investigate IL transport within wood fibers and the diffusion of lignin into cellulose fibers. Softwood (Norway spruce) samples are exposed to PILs (e.g., N,N-Dimethylbutylammonium hydrogen sulfate, [DMBA][HSO4]) at specific time-temperature combinations. Wood sections are obtained and characterized by the localization of PILs and wood components within cell walls. A multiscale characterization approach using Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) and Wide/Small-Angle X-ray Scattering (W/SAXS) will provide both chemical and morphological insights supporting wood components transfer events understanding. By integrating these techniques, this study elucidates the interplay between the topochemistry of ionoSolv process and the associated morphological changes in wood ultrastructure. Ultimately, this will enable the full utilization of the unique properties of ionic liquids for resource-efficient and optimized processing design.