ABSTRACT Due to the fact that raw timber has permeability characteristics unsuitable for some applications, several processing techniques have been developed, such as hydrothermal treatments and freezing, which aim to improve these properties. The objective of this study was to analyze the effects of treatment temperature and duration on the permeability of Eucalyptus grandis wood. Heartwood samples from three E. grandis trees were utilized, each with the dimensions 30 x 8 x 3 (length, width, thickness). The treatments were carried out at three temperatures (-20°C, 60°C, and 100°C) and three exposure durations (5, 10, and 15 hours). Treatments at -20°C were conducted inside a domestic freezer, while treatments at 60°C and 100°C took place inside a Parr Reactor, while the wood being submerged in water. Extractive removal was only observed at the surface and interior of wood treated at 60°C and 100°C; while all treatment conditions increased permeability with respect to control treatments.