This study investigated the thermal properties of Oriental beech (Fagus orientalis) treated with (NH4)2HPO4, K2HPO4, NH4Cl and (NH4)2SO4 salts and their mixtures (1:1; w/w) aqueous solutions at 3% concentrations. The effects of different inorganic salts fire retardants on the thermal degradation characteristics of wood samples were evaluated by thermogravimetric analysis (TGA). Based on the TGA curve for untreated beech wood, weight loss takes place at three distinct steps. The impregnation of inorganic salts resulted in higher char yields and additional thermal degradation steps were identified. The highest char yield (80%) was obtained from (NH4)2HPO4-K2HPO4 mixture impregnated sample.  Salt mixtures containing phosphates ((NH4)2HPO4 and K2HPO4) have remarkable effects on thermal stability of beech wood, whereas NH4Cl salt lowered the decomposition temperatures and char yield.