This study focuses on the effect on wood strength and natural durability of Eucalyptus globulus and Eucalyptus botryoides when subjected to heat treatments with low energy consumption. The objective was to improve the wood durability, without negatively impacting the strength properties. Six-year-old trees from Eucalyptus globulus and Eucalyptus botryoides were used. The samples were heat treated for 4 h conditioned to very low oxygen availability. A field test for assessing the resistance to termites and fungal degradation was conducted according to EN 252:1989/AC1:1989 Inspections were made every six months for 3 years. All the samples of Eucalyptus globulus showed signs of termite and microorganisms attack, most showing extensive galleries. Eucalyptus botryoides wood showed no sign of termite attack and only few traces of microrganisms presence. The wood bending strength was smaller upon thermal treatment for both species, decreasing 3.8% and 4.8% for Eucalyptus globulus and Eucalyptus botryoides, respectively. Overall the results are promising regarding some common utilizations, mainly floor coverings, decks, doors and door and window frames, fences (only for Eucalyptus botryoides), decorative arbors and pergolas (only for Eucalyptus botryoides), but excluding structural beams for building roofs or bridges due to the fragility of the wood treated thermally towards impacts.