Pine (Pinus sylvestris) and spruce (Picea abies) of Swedish origin has been heat-treated according to a process intended for above-ground end-uses. Tests have been carried out in order to study and evaluate the durability of the heat-treated material against decay and discolouring micro-organisms as well as technical and other properties, such as bending strength, stiffness, delamination of glulam, withdrawal load for fasteners and chemical emissions. The tests have shown that the bending strength has been reduced by approximately 50 % whereas the stiffness has been much less affected. Thus, the use of heat-treated wood where the strength is a decisive property should be carefully considered. There is an indication that the withdrawal load for fasteners for heat-treated wood is lower than for untreated wood. Gluing of heat-treated wood needs particular consideration, and PVAc adhesives seems to be unsuitable for gluing heat-treated wood. Chemical emissions (VOCs) were very low and will not be any major problem, providing proper conditioning is carried out after treatment. Heat-treated wood seems to be less susceptible to attack by discolouring micro-organisms than untreated wood. The decay tests in the laboratory and in the field have not yet given an unambiguous answer concerning the performance in various end-uses. However, the use of heat-treated wood in ground contact should be avoided.