The use of wood and wood based materials in moist environments is limited because of these material’s susceptibility to decay fungi. The durability thus needs to be improved, which can be achieved by chemical wood modification. The exact mechanisms behind the increased durability of modified wood is however not known, but the lowered moisture content is an important factor. Not only the amount of water influences degradation processes, also the state/location of water plays an important role, but this is less explored. The purpose of this project is to significantly advance the understanding of the interaction between modified wood and water with special focus on high relative humidity levels relevant for fungal degradation. This knowledge is needed to obtain a better understanding of how to design efficient wood modifications that limit the ability of fungi to degrade wood. The studies will be performed on wood that is modified in two ways: one modification that affects both cell wall water and capillary water and one that only affects the capillary water. By using careful conditioning procedures and a unique combination of methods, influence of the modifications on water in different states/locations will be studied at high moisture levels. In addition, studies on how the state/location of water influences degradation will be performed.