Analysis of the gases, vapour and degradation volatiles emitted as smoke from the welding interface during linear vibration welding of beech and oak woods has shown that the compounds in such a smoke are water vapour, CO2, and degradation compounds from wood polymeric carbohydrates as well as from amorphous lignin. For the two hardwoods tested the main carbohydrates contributing to the volatile compounds are xylan hemicelluloses. Numerous compounds, in very small proportions, derived from the degradation and rearrangement reactions of lignin have also been identified. The proportion of CO2 emitted is very low, and neither CO nor methane are emitted due to the relatively low temperature reached. Experiments in the temperature range of linear wood welding but at prolonged time have shown that the main component of the smoke produced during welding appears to be water vapour. There is no emission of gases or degradation volatiles after welding has ended.