In this study, the effect of log steaming and veneer drying on acetyl group content of wood and subsequent formaldehyde emission of plywood produced were investigated. This work was carried out on pine (Pinus brutia Ten.) and beech (Fagus oriantalis Lipsky) species. Changes in acetyl group contents were determined by Freudenberg method and IR-spectra. Formaldehyde emission was determined by WKI-bottle and perferator methods. Pronounced changes were observed in acetyl group contents due to log steaming and veneer drying. Amount of formaldehyde emission occuring in pine plywood was found to be higher than that of the beech plywood. Lower formaldehyde emission was obtained in plywoods produced using veneers with rich acetyl group content.