Pyrolysis plays a vital role in biomass conversion; it is one of the most promising thermal conversion routes. Solid, liquid, and gaseous products are obtained from biomass pyrolysis. The obtained liquid is considered to be a perspective fuel; however, direct use of bio-oil as fuel may present many difficulties due to its high viscosity, poor heating value, and relative instability. This creates a significant economic barrier for production of transportation fuel by pyrolysis process. Catalytic pyrolysis has been widely used as a convenient method for the direct conversion of biomass into higher quality liquid bio-fuels. In this study, intermediate pyrolysis of cellulose (as a model substance for biomass) with or without catalysts was investigated using TGA-FTIR method in order to determine the influence of zeolite on the relative yield of the compounds. The addition of zeolite with medium and weak acidity increased the production of volatile matter from 86.1 % to 88.5 % and 88.9 % under the catalysts MCM-41 and ZSM-5 (70). Zeolite with high acidity contributes to the formation of coke and simultaneously causes the deactivation of the catalyst, thus decreasing the volatile matter yield from 86.1 % to 83.6 % and 83.2 % by using H-ZSM-5 (23) and H-ZSM-5 (50). All catalysts showed deoxygenation activity. Zeolites had higher activity in the deoxygenation of compounds containing hydroxyl group than compounds containing carbonyl and carboxyl groups. H-ZSM-5 (23) had a substantial effect on the production of monoaromatic hydrocarbons, whereas the yield of olefins notably increased in the presence of ZSM-5 (70).