Abstract The course of pyrolysis process of 5 different biomass wastes including agricultural waste [soft wood (SW), sunflower husks (SH), corn stalks (CS), walnut shells (WN), and wheat straw (WS)] was investigated using TG/FT-IR. The studied samples were carbonized in a steel retort in the absence of air during heating to the temperatures of 300, 400, and 1000 °C. The biomass samples were extracted by a mixture of chloroform and methanol in a microwave extractor under the pressure of 18 bar at the temperature of 150 °C. The samples heated to the temperature of 1000 °C were studied using X-ray diffraction. The obtained results suggest that the temperature of the maximum on the curve of the mass loss rate shifts towards higher temperatures with an increase in mass at the temperature of 750 °C for the studied samples. On the basis of the comparison of the composition of volatile products of pyrolysis at the temperature of 300 °C and the analysis of the ATR spectra of biochar pyrolyzed at the temperature 300 °C it was determined that the content of compounds from the extracted material in the composition of the volatile products of pyrolysis amounts to about 1/8 for SW sample, for WN sample – 1/6, for CS sample – 1/5, and about ¼ for SH sample. The biochar from WN sample had the greatest degree of structural ordering. It is suggested that both amount of volatile products released during pyrolysis and content of inorganic components influenced the degree of structural ordering of biochar of the studied samples.