A real time fast evolved gas analysis/Fourier Transform infrared (FAST EGA/FTIR) method was developed and applied to study the gas phase component evolution of cellulose pyrolysis. Experiments were conducted under different pyrolytic conditions. Efforts were made to achieve a better controlled heating environment and sample temperature measurement. Heating rate, purge gas flow rate, and the residence time of the vapor phase in the heated zone were found to have a significant effect on the formation of final gas compounds during cellulose pyrolysis. This technique provides not only a method to analyze the evolved gas in real time, but also information on reaction mechanisms as well as a way to distinguish and control of primary and secondary reactions. Experimental apparatus and data on several gas compounds evolved during cellulose pyrolysis will be discussed.