Abstract Active functional groups and interactions involved in the sorption of Li⁺ ions from an aqueous LiCl solution onto the Norway spruce sapwood (sW) flour have been investigated. To this purpose, sW was delignified by peracetic acid (PAA) treatments and the resulting holocelluloses (HC_{6 h}, HC_{24 h}, HC_{51 h}, HC_{72 h}, where the lower case data indicate the PAA treatment time) with various lignin contents were immersed in aqueous solution of LiCl and the sorption effects were studied by flame atomic emission spectroscopy (FAES), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). The Brunauer- Emmett-Teller (BET) specific surface area increased from 1.5±0.0 m²g⁻¹ to 2.4±0.1 m²g⁻¹ for HC_{6 h}, and from 1.6±0.03 m²g⁻¹ to 2.7±0.6 m²g⁻¹ for HC_{72 h} upon LiCl treatment. It was found that Li⁺/Cl⁻ retention occurs predominantly via O-containing functionalities and the carbohydrate-rich samples sorbed more Li⁺. Upon LiCl treatment, the mobility and accessibility of the wood matrix was enhanced, possibly by interference of the introduced ions with the existing intermolecular bonds.