Microwave treatment of wood has been used with several aims in many studies as drying, enhancement of pulp properties, angle fibre detecting, density evaluation, etc., and also to improve permeability of wood. Eucalyptus globulus Labill. is a refractory species which is spreading its use as solid wood for construction in Spain. Studies of different ways to improve their impregnability (uptake and retention) are relevant for that sector. This study analyse the suitable intensity of microwave treatment focus on Eucalyptus wood oriented to this target but avoiding cause damage to its structure. A total of 7 groups of 50 specimens each (20x30x3500mm3) were used. The initial moisture of the sample have to be considered so four of them were dried an approximate moisture content of 12%, including reference one, and three remain wet (above 30% moisture content). Treatment times were defined according to wood volume and in order to achieve several energies (290, 360, 430 MJ/m3). Finally samples were autoclaved after head-sealed. Uptake rates (%) and retention (kg/m3) were calculated. The results of moisture decrease show that microwave treatment is a good method to dry this species. Both uptake and retention values increase respect reference sample but the most relevant records are obtained in wet samples and higher intensity. Microwave treatment reveals as a useful tool for getting better impregnability of Eucalyptus globulus L. from Spain. Among the energies applied, 430 MJ/m3 produce better results mainly in green samples. Studies related to suitable energies considering commercial size have to be the aims in future projects.

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