Thermochemical conversion processes include three subcategories: pyrolysis, gasification, and liquefaction. Pyrolysis plays a vital role in the biomass conversion as one of the promising thermal conversion routes. Non-condensable gases, bio-oil, and solid char are obtained from biomass pyrolysis. The rapidly evolving research direction to upgrade pyrolysis bio-oil into high quality liquid bio-fuels - bio-oil with high content of aromatic and aliphatic hydrocarbons. The intermediate pyrolysis using low quality feedstocks was poorly studied. The thesis describes the thermal and catalytic intermediate pyrolysis of buckwheat and wheat straws and wheat bran by using TG-FTIR method. We found that the higher heating rate and temperature on the pyrolysis provide the higher content of hydrocarbons, anhydrosugars and phenols and lowest content of acids in bio-oil from regardless feedstocks. In this study, the ability of zeolites (ZSM-5, MCM-41), noble-metals (5% Pt/C, 5%Pd/C), nanopowders (NiFe2O4, Ni-Al2O3, NiAl2O4, Ni-MnAl2O4, Ni-MgO, Fe3O4), and inorganic calcium - based catalysts (CaO, Ca(OH)2, CaCO3, calcined dolomite of 850 °C) to catalyzed deoxygenation reactins on the pyrolysis from feedstocks were studied. The results of experiments showed that the inorganic calcium based catalysts partly improved the composition of bio-oil by reducing content of organic acids. The zeolites didn't promote content of anhydrosugars and phenols in bio-oil but those are suistable to obtain bio-oil with higher content of hydrocarbons. The platinum group catalysts are more active at lower temperature on the pyrolysis than zeolites, nanopowders, and inorganic calcium-based catalysts. Those intense able to reduced carboxyl and carbonyl groups containing compounds thus stabilizing bio-oil. In this study, all of nickel containing nanopowders can able to reduce the solid residue from biomass pyrolysis processes. Nanopowders are suitable for the production of bio-oil with high hydrocarbon content. To summarize the results of the study, we found that the ZSM-5 and 5% Pd/C give the highest hydrocarbon in the bio-oil from wheat straw pyrolysis at 700 °C.