The study is focused on an experimental investigation of the effect of impregnation and heat treating of oak (Quercus petraea L.) and pine (Pinus sylvestris L.) samples on bending strength, bonding strength, dowel holds performance, screw holds performance, dowel-joint performance and tenon and mortise-joint performance. The solution of 5 % natural oak tannin was used for impregnation. Heat treatment process was performed at 212 degrees C. Bending and bonding strength have increased on impregnated oak and decreased on pine. A dowel holds, a screw holds, a dowel joints and a tenon and mortise-joint performances of all impregnated samples have been reduced. Thermo process caused a reduction of technological properties for both wood types. A combination of thermo and impregnation processes caused variable performances of oak and pine samples in relation to measured values.