AbstractMethylolurea and carbamide were used to impregnate eucalyptus wood to improve its physical and chemical properties. The physical properties and dimensional stability were examined. TGA was used to evaluate the thermal stability of the wood. FTIR was used to state the changes of functional groups. The changes of wood structure were observed by SEM. The results showed the bending strength and compressive strength parallel to the grain by 15.10% and 16.78%, respectively. The basic density of modified wood was improved by 14.29%. The shrinkage of volume and swelling of volume were significantly decreased to the untreated wood. The TGA results indicated that the mass loss was around 8% during the second stage, from 120°C up to 280°C, while the mass loss of treated wood was around 4%. The treated wood exhibited LOI (limited oxygen index) values of about 42%, while the natural wood exhibited a LOI value of 22%. he FTIR analysis successfully showed that chemical bond was produced between wood and methylolurea as a result of chemical reaction between wood and methylolurea. The SEM results indicated that the transverse and tangential sections of the treated specimens were filled with the reaction products, which can prevent the absorption of moisture.