Industrial heat treatment technology for wood has been under development since the 1970s. The technology consists in heating wood to temperatures of from 150°C to 240°C while preventing it from burning. This is achieved by heating the wood in either an inert atmosphere or saturated vapour environment. Heating the wood over 200°C changes the chemical structure of the wood and results in a reduction in its hydrophilic behaviour. After heat treatment when wood colour has changed to brown, an improvement in dimensional stability and biological durability should be observed. However, some mechanical properties of the wood may have decreased. This enhanced dimensional stability and biological durability make heat treatment an interesting option for the protection of wood used in exterior applications. The objectives of this study are to assess the performance of heat treatment technologies and to determine the properties of jack pine and balsam fir after heat treatment, as regards to exterior applications. Owing to difficulties in the start-up period that significantly delayed the project, no experimental work had been conducted by the end of March 2003. The lumber has however been sent to two companies for treatment and the physical and mechanical tests will be conducted under a new project entitled “Quality Control and Certification of Thermally Modified Wood.” A final report will be issued at the end of March 2004.