Simultaneous Thermal Analysis (STA, TGA and DSC) unifies the simultaneous application of thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) to one and the same wood sample in a single instrument, under perfectly identical conditions – same atmosphere, gas flow rate, pressure, heating rate, thermal contact, etc. New thermal analysis approaches for integral distinguishing between the flaming and glowing combustion of wood were discussed. The results obtained by STA were used in a new way in order to reveal the influence of plasma-aided capillary impregnation on thermal decomposition and glowing of wood controlled by oxygen and nitrogen containing flame re- tardant. New integral criterion of thermal behavior and decomposition such as specific enthalpy change has been developed by investigating samples of European White Pine (Pinus Sylvestris, Bulgaria) wood. This study has been developed also as part of a large investigation on plas- ma-chemically activated (polarized, functionalized) wood surface and its capillary impregnation with nitrogen- and phosphor flame retardant containing water solution.