One of the newer commercial technologies to provide stability and durability to wood and wood composites is the process of acetylation (the reaction of acetic anhydride with wood). Wood is often used in contact with concrete, although only a very limited amount of species are suitable for this type of application because of durability issues. From this perspective durability class 1 timber such as Accoya®, is well suited to the application. The research topic in this paper relates to concern that acetylated wood may suffer a reduction in acetyl level when used in contact with concrete, due to the alkaline nature of concrete and the sensitivity of acetyl groups to alkaline conditions. Acetyl groups are known to be sensitive to pH’s greater than 7. To determine if acetylated wood can be safely used in contact with concrete without the loss of acetyl content, a series of experiments were conducted using both dry and wet samples in contact with concrete. The results show that there is no loss of acetyl when the acetylated samples were kept dry in contact with concrete and also no loss when samples were cycled for three and six months between wet and dry conditions.