Thermal degradation and kinetics of the untreated, alkali treated and sulphuric acid treated sugar cane bagasse (SB) have been evaluated using a non-isothermal thermogravimetric analysis under nitrogen atmosphere. Both alkali and sulphuric acid treatments affected the initial chemical composition and the structure of the untreated SB. The alkali treated sample showed the highest values of thermal degradation activation energy in all the investigated degree of conversions with an intense increase from 30% to approximately 50% mass loss, which is in agreement with its higher thermal stabilities. However, the acid treated sample showed a change in activation energy at around 40% mass loss, to lower values with an increase in degree of conversions.