Thesis researches the influence of composition of adhesive mixture based on liquefied wood on bonding quality of heat-treated wood. We observed the effect of modification on mechanical and physical performance of wood. Using standard methods we determined the shear strength of specimens (SIST EN 392), modulus of elasticity, modulus of rupture (SIST EN 408) and delamination (SIST EN 391). Tests were performed on heat-treated and non-treated 3-layer spruce laminations glued with 6 adhesive mixtures. We used MUF adhesive and poplar liquefied wood. 6 different shares of poplar liquefied wood: 0 %, 5 %, 15 %, 25 %, 35 % and 50 % in mixture were used. We found out that the quality of adhesive of heat-treated wood depended on usage of adhesive mixture. Higher the share of liquefied wood in adhesive mixture, lower the strength. We determined that heat-treated wood had lower modulus of rupture comparing to non-modified wood. Equilibrium moisture content of heat-treated wood in a standard climate was for 3.5 % lower from that of non-modified wood.