Thermally modified wood protected by a transparent coating is still susceptible to surface degradation due to influence of environmental factors. In this paper, the possibility of increasing the durability of transparent coating on thermally modified wood by adding TiO2 and ZnO nanoparticles in waterborne polyacrylate coating was analysed. Unmodified and thermally modified beech wood samples uncoated and coated with nine waterborne polyacrylate coatings were exposed to environmental influences. Measurements of color, gloss, cracking, peeling and mildew, mechanical and thermal properties, coatings transmittance and chemical changes were conducted.This study showed that the thermal modification beech reduced density, increased acidity, markedly reduced the polar component of surface free energy, increased the content of lignin, water and solvent extract. Addition of ZnO nanoparticles had a greater impact on the properties of waterborne polyacrylate coating than TiO2 nanoparticles. Addition of ZnO nanoparticles increased the viscosity and pH of coating. TiO2 and ZnO nanoparticles increased strength, modulus of elasticity and glass transition temperature, and reduced stretching of waterborne polyacrylate coating. Addition of TiO2 and ZnO nanoparticles in waterborne polyacrylate coating reduced colour change of thermally modified wood - coating system during natural and accelerated exposure, but it was still very pronounced and clearly visible to the naked eye. Better stabilization effect of colour change was achieved with TiO2 nanoparticles and with increasing the concentration of nanoparticles. Pretreatment of thermally modified beech wood with HALS compounds did not protect thermally modified beech wood against colour change during natural and accelerated exposure. Adding of pigments in coatings with TiO2 and ZnO nanoparticles stabilised colour of thermally modified beech wood during accelerated exposure the most and during natural exposure pigments increased colour stability of wood samples coated with coating with ZnO nanoparticles. Addition of TiO2 and ZnO nanoparticles in waterborne polyacrylate coating did not reduce chemical changes of thermally modified wood coating system during natural and accelerated exposure, while the chemical changes were reduced with combination of pigments and TiO2 and ZnO nanoparticles. Extractives contributed to the higher colour change of thermally modified wood at a higher temperature (212 C) during accelerated exposure, which was also visible in change of peak at 1595 cm-1.