After removing inorganic metals from poplar wood via demineralization with diverse solvents [HCl, HF, distilled water (DI-H2O)], respectively, changes in decomposition characteristics, maximum decomposition rate (Vmax) and corresponding temperature (Tmax), were observed using thermo-gravimetric analysis. Activation energies calculated by differential method were ranged from 160.5 to 188.1 kJ/mol for raw biomass, 157.5 to 233.2 kJ/mol for HCl-biomass, 172.3 to 220.3 kJ/mol for HF-biomass and 127.9 to 229.0 kJ/mol for DI-H2O-biomass. The demineralized samples were also subjected to TGA analysis after impregnation with K, Ca, and Mg. Interestingly; only potassium had catalytic effects on cellulose decomposition. A significant decrease in Tmax was attributable to an increase in potassium content.