The objective of the paper was to determine the effect of an alkyd resin in a grafting process of [3-(2-aminoethylamino)propyl]trimethoxysilane (AAPTMS) to the wood matrix. In order to define the character of bonds between wood and the silane-resin formulation, nuclear magnetic resonance was applied. Fourier transform infrared spectroscopy analysis detected vibrations of Si–C, Si–O and N–H groups, indicating permanent bonding wood with the silane-resin formulation. Atomic absorption spectrometry and an elemental analyzer were used to evaluate the degree of leaching of silicon compounds from treated wood. The results of chemical analyses confirmed that the silane-resin formulation grafted to wood and that AAPTMS without an addition of the resin did not bond with wood and was leached from the treated material. The results of analyses described in the paper indicated that the alkyd resin significantly limited leaching of the organosilane from treated wood and improved its bonding with the wood matrix.