Durability, haptic, and optical appearance of wood are improved by coatings, which are nowadays prepared using environmentally compatible and less health-damaging materials. However, contemporary wood coatings have frequently a shortened service life compared to their traditional predecessors. New coating formulations would have a better performance if the adhesion to wood could be improved. In the present work, the chemical interaction between a titanium-based coupling agent, isopropyl triisostearoyl titanate (titanium agent, TA) and lignin has been studied by means of attenuated total reflectance-fourier transform infrared spectroscopy in combination with first principle predictions based on the density functional theory (DFT). In the infrared spectra, a new band at 1586 cm-1 was identified and the DFT predictions confirmed that the new band is because of the covalent bonds in the form of ether linkages between TA and lignin.