In this contribution, the impregnation of wood with a paraffinic phase change material (PCM) is investigated, specifically to increase the heat capacity of solid wood, which significantly influences the thermal inertia when used in buildings. Four wood species (beech, poplar, oak and spruce) were impregnated with different pressure processes in an autoclave. For poplar, up to 480 kg of PCM per m³ of wood was deposited. For beech and spruce, also more than 200 kg of PCM per m³ of wood was achieved. However, oak was hard to impregnate and only about 100 kg of PCM per m³ was deposited. Leakage, which is undesired, occurred for all the wood species, especially for beech, but could be significantly reduced to less than 10% by increasing the viscosity of the PCM. The heat capacity was increased by one order of magnitude compared to clear wood, as measurements with differential scanning calorimetry showed. Simulations with an analytical model demonstrate the potential for damping temperature amplitudes in buildings in the summer month when applying PCM.