AbstractThis paper reviews recent results in the field of chemical modification of wood with linear chain anhydrides. Though the main focus is on work performed by the author, this is described in the context of related progress in the field. The combined research has demonstrated the effectiveness of chemical modification applied to solid wood and wood raw material for composites production in overcoming the main disadvantages of wood. Wood samples and wood chips/strands have been chemically modified with a series of anhydrides at equivalent levels of modification, under identical conditions, and the question was to determine which is the primary factor controlling the biological durability, the degree of cell wall bulking by the bonded adduct, or the extent of hydroxyl substitution. The results have clearly indicated that the degree of cell wall bulking caused by the adduct, rather than the extent of hydroxyl substitution, is the primary factor controlling the biological durability and water vapour sorption. Despite the large difference in OH substitution level, reaction with different anhydrides results in the same level of protection against decay, marine borers and termites, and in the same level of water vapour sorption. These observations suggest that the mechanism of protection is not chemical/biochemical in origin, but relates to the bulking of the cell wall by the reacted adduct.