<p>The aim of this study was to improve the flame retardation and performance characteristics of wood through impregnation with magnesium-based compounds. Fir wood (<i>Abies sp.</i>) samples, both heat-treated and non-heat-treated, were impregnated with magnesium oxide and magnesium chloride using combined and separate methods. Impregnation was carried out under an initial vacuum followed by pressure. The effects of impregnation on the wood's structure, thermal properties, and fire resistance were investigated using FTIR spectroscopy, XRD analysis, TGA analysis, and flame retardation tests. FTIR, XRD, and TGA analyses confirmed increased thermal stability and crystallinity in impregnated samples, especially non-heat-treated samples. Wood impregnation with magnesium compounds extended the time to ignition, reduced flame duration, and decreased glowing combustion duration. Impregnation of samples resulted in a less carbonized surface. The lowest carbonized surface was observed in the combined-method impregnated non-heat-treated sample. Based on the results of this study, it can be concluded that the impregnation of heat-treated and non-heat-treated wood with magnesium compounds (oxide and chloride) was successful in improving flame retardation and performance characteristics.</p>