Natural material such as wood is today increasingly used in structural applications. Because of its general applicability, its properties and more ecological awareness, the popularity of timber is growing. Unfortunately, all the wood species are not sufficiently resistant, and therefore less resistant species require additional protection. In our experiment we use less resistant spruce. Samples were first thermally modified, the process of modification was held at temperatures of 210 °C and 230 °C. Than samples were treated with the methyl methacrylate (MMA). We impregnated after three different procedures, with different concentrations of MMA with and without inhibitor. The variables in the procedures of impregnation were time, temperature and pressure. The influence of thermal modification, the method of impregnation and concentration of MMA on the water absorption, water vapour and sorption properties of treated wood were studied. It is known that thermal modification has a greater degree of influence on the mass loss of the samples and thus the deterioration of the mechanical properties of wood. However, it has got a positive effect on the resistance against fungi, insects and weather influence. The treatment with MMA slightly reduces absorption of water and increase the hydrophobicity of the treated wood, while it has no influence on the absorption of water vapour.