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Chemical modified wood particles used to particleboards manufacture may, at the same time, improve the dimensional stability and damage the internal bond. The aim of this research was find the optimal point of acetylation for particleboards. Pinus taeda particles with different degrees of acetylation, 8, 15 and 20% of weight percentage gain (WGP), were used in the production of particleboards with urea-formaldehyde resin and wood-cement composites produced by mechanical and vibratory compaction. It was evaluated the water absorption, thickness swelling and internal bind of the particleboards according to the European standards EN 317 and EN 319. Particleboards produced with 15 WPG showed the lowest water absorption and thickness swelling values. However, the use of chemically modified wood had a negative influence in the internal bind of the boards. This phenomenon can be explain due to the similar behavior between resin and water, that way, the high degree acetylation stops the adhesive and adherent bind. In the case of wood-cement composites, the internal bind improves as the acetylation degrees get higher. Nevertheless the inhibition of acetylated wood particles to the cement hydration got higher when the WPG was higher than 8%.